Other Risk of Rain 2 Guides:
- How to Unlock REX.
- How to Unlock All Characters.
- Beginner's Guide (Tips and Tricks).
- Altar of Gold, Gilded Coast and the Aurelionite.
- Basic Guide about REX's Cancels and Properties.
- Shrine / Environment Guide.
- How to Find Teleporters.
- Newt Alter locations.
- All Items Tier List.
- Survivor Tier List.
- Mercenary Guide.
- Huntress Guide.
- Engineer Guide.
- Artificer Guide.
Note: I haven't played REX that much yet. I only unlocked them a couple days ago, which I guess isn't much more than anyone else at this point. Do not take this guide as the be-all-end-all of strategy for this character; this is just what works for me and should hopefully give some insight into the character in general. If you build your own play style off of this, then arguably I've done my job even better than just telling you all this.
Also note: plural pronouns and verbs are used for REX throughout the guide because the lore indicates that REX is both the plant and the robot. Don't get on my case for this.
How to Unlock
Oh boy, this is a tough one. You cannot unlock REX as MUL-T (presumably for balance reasons) but you can do it on any difficulty.
So, first of all, once you get out of the pod, look around the back for a panel.
Open the panel and take the Fuel Array inside. This takes up your equipment slot. You must carry the Fuel Array all the way to the fourth level. This is made more difficult by the fact that the Fuel Array will explode if you go below 50% HP or take too much damage in a single hit, killing you. I highly recommend doing this on Drizzle and playing a durable character like Engineer as a result.
Once you get to the fourth stage, use jump pads to get to the upper level. You should see a taller plant on this level that you can interact with. Hit E to use the Fuel Array on it. Congratulations, you've just unlocked REX! Now all you have to do is finish the run (in whatever manner you choose) and you can play as your new character.
The Basics of REX
REX carry a unique status effect with them called "Weaken," which reduces enemy's movement speed, defense and damage for a little bit. You can spread this in a couple of different ways (through your primary and your utility skills), and doing this is a huge boon for your team. Who doesn't like to take less damage and deal more in turn? Exactly. This gives REX the feel of a support character, but REX can carry by themselves thanks to this and their most prominent feature, the ability to heal themselves with several of their attacks. This also helps to offset the HP cost of two of their abilities, as well.
REX's primary talent as fighters is in dealing with tightly packed enemies due to their secondary and ultimate skills both affecting an AoE (the ult is pretty big; your secondary, less so). If someone gets a bunch of enemies into a group for you (or, say, everything goes after an Engineer's turret -- less common in RoR2 than the original, I've found, but still a possibility), you can set up for some huge damage potential. Alternately, you can use your skills to set this up for you because they can help move enemies around, then spam your secondary for lots of DPS.
Overall, REX form a strong, versatile character that can fit into almost any team build, with different needs from a lot of other characters (thus making them easier to fit them into teams). The challenge to unlock these little guys? Well worth it.
Primary (M1): DIRECTIVE: Inject - "Fires 3 syringes for 3x80% damage. The last syirnge Weakens and heals for 30% of damage dealt." This actually might not be your bread and butter depending on how you build, not unlike the Artificer, who often has to juggle all her skills early on due to running out of fire blasts. However, your primary is pretty good, but the refire rate is abysmal. I thought you couldn't hold the mouse button to get a refire rate at first, it's that bad.
Note that the three syringe shots fan out slightly in a horizontal line, so the second syringe goes right down the middle of your aim, while the first is slightly to the left and the second is slightly to the right. If all you want to do is land the debuff, keep this in mind.
Secondary (M2): Seed Barrage - "Costs 15% of your current health. Launch a mortar into the sky for 450% damage." Well, "mortar" is misleading. You target an area and a thing drops out of the sky and explodes on that. This ignores ceilings and stuff, otherwise it would probably be useless on stage 4. Importantly, Seed Barrage does a ton of damage, and its low cooldown (a second or less!) makes it incredibly spammable. So it's kind of an actual barrage.
15% of your current HP sounds intimidating, but it's not horrible with some recovery items -- this self-damage procs on-damage effects for items like Medkit and Brittle Crown -- and with the effects of your healing skills. REX have a surprising amount of sustain despite hurting themselves constantly.
Seed Barrage has a ridiculous range, by the way, so it's not a bad idea to get into a position and play sniper. Not... not like RoR1 Sniper, your damage ain't quite that high, but you know what I mean.
Utility (Shift): DIRECTIVE: Disperse - "Fire a sonic boom that pushes and Weakens all enemies hit. Pushes you backwards if you are airborne." I don't use this a whole lot, but it's very good for increasing the distance between you and enemies or, better yet, pushing them all together so you can hit them all with one big attack.
Ultimate (R, "ult"): Tangling Growth: Costs 25% of your current health. Fires a flower that roots for 200% damage. Heals for every target hit. Again, "root" is kind of a misleading term -- it's more of a tether. Enemies can still move around a little, but only inside of the sphere of influence of the flower. Using the shockwave to push enemies into this if you can is a good idea.
Note that you will continue to leech from dead enemies in the area of your ult. Not sure why this is, but every little bit helps, because 25% of your current HP is a pretty intimidating cost even with a lot of healing.
Your ult does a ton of damage over time (it lasts for 8 seconds or so) over a decently-sized area. This means that early game Trials of the Mountain are very easy, most of the time, since you can usually easily snare multiple bosses. If you see one on the first level, take it, because it's basically free real estate.
With an 11-second cooldown ant an 8-second duration, this ability has a great uptime. It's a good choice any time there's a large group of enemies clustered nearby, and you can usually get away with having it down for a second or two. Even so, though, don't waste it too freely; you should try to use it almost exclusively when you can catch 4+ enemies at once.
Items are sorted by rarity, then by priority. "Priority" refers mostly to how high priority they are for you to get vs. the rest of your team in multiplayer; purchasing priority is usually discussed in the item notes.
REX have some flexibility in terms of build, and a few unique properties that throw the priorities of some items out of whack. Just like how the Engineer's stationary turrets make the Bustling Fungus a high-value item, REX's HP-cost skills proc Medkits and make them a lot more appealing of a pick-up. Furthermore, the low cooldown on their right-click means that, unlike some characters, they're noticeably less greedy for Backup Magazines. Your team's Artificer will be happy about this, anyway, but you might want to consider grabbing one or two for some builds.
Like anybody else, REX can build for equipment use. You should only do this if you picked up a really good piece of equipment, like the Royal Capacitor. Enough cooldown reduction makes the Lunar equipment Spinel Tonic extremely viable by basically making it so you don't have to ever worry about dealing with the potential debuff.
High Or Zero-Priority Common
Backup Magazine: I have a feeling this is going to be the strategy that becomes meta for REX, but I'm not a huge fan myself. Backup magazines make it easier to spam your M2 with impunity due to its 1s cooldown. One to two should be all your need, but I'd have to test more. Be careful with this. I highly recommend stacking medkits if you to this.
Top Priority Commons
Medkit: I've explained this one already, but you are basically assured to get the most out of it, and making your skills "cheaper" is never a bad thing.
Tougher Times: You should take at least one of these early on if you can. Though it cannot block self-damage (as far as I know...), it will give you a little more survivability -- and with your running on low HP often, you need as much as you can get.
High Priority Commons
Paul's Goat Hoof: You are slow. Fix that. (Don't hog 'em, though.)
Energy Drink: You are still slow. Fix that more.
Soldier's Syringe: So, that description for your M1 sounds really good, right? Well, bad news: its refire rate is trash. Grab one or two of these to make it more useful.
Lens-Maker's Glasses: I mean, did you see how much damage your M2 does? Grabbing a couple of these is a good idea. Anybody else with high damage single hits, like the Artificer, should trade off with you over these for a little bit.
Average Priority Commons
Monster Tooth: Look, don't buy these if there are better options, but everyone in your party should grab some as you go.
Warbanner: As discussed, your M1's refire rate sucks eggs. Getting one of these set up is useful in an area where you need to make a stand, such as around the teleporter. However, anyone can fairly carry this, and you never need more than one. (It also doesn't give bonus regen like it did in the first game, which I still think is a load of crap.)
Tri-Tip Dagger: Share these evenly with the rest of your team, because basically everyone uses multi-hit attacks in RoR2.
Gasoline: Okay, hear me out, though: AoE damage effects are super good with your ult. You really only need one of these, so I'm not putting them at a higher priority bracket, but bump it up early on.
Personal Shield Generator: Good item. Adds durability without adding "real" HP.
Old Guillotine: This helps you kill elites more easily, so you should definitely grab it; it's here because everyone wants them basically equally.
Armor-Piercing Rounds: More overall bonus damage to bosses than the Crowbar, so I put this at a higher tier. These are a very strong item that give you good consistency.
Bundle of Fireworks: If you have a 3D printer on a level with these, you have yourself the most hilarious level in the game. Otherwise, this is mostly just a nice sweetener that makes doing normal stuff in the game have a little extra reward. Who's gonna argue with that salvo at the beginning of a teleporter event? Not me.
Topaz Brooch: This is extra-nice for REX because they tend to kill large groups of enemies all at once. One well-placed ult gives you basically a second health bar for a few seconds. Hard to argue with that, isn't it? (NOTE: You can use shield to pay for skills, at least with this -- but I tend not to notice due to combat situations getting hectic pretty fast on the higher difficulties.)
Low Priority Commons
Cautious Slug: In my experience, this isn't active often enough to warrant choosing over other items in the shop if available.
Bustling Fungus: Actually pretty good on you, since REX can entrench somewhere and M2 until the cows come home from afar -- but eventually, you will have to start kiting, and when that time comes, the Fungus becomes worthless, and having used that strat earlier may have put you in some danger depending on how hard you've stacked these.
Stun Grenade: I've been told this is slept-on and better than the RoR1 variant. I don't see it. This also doesn't activate often enough for me to like it, so you have to stack a lot of them.
Sticky Bomb: Strong, but a 5% chance of activating makes this not a great choice, even if stacking raises the odds.
Rusted Key: Pick them up if you see them, but buying them is unnecessary. It doesn't matter who holds them, the chances on items you get out of the boxes count how many keys the whole party has.
High Priority Uncommons
Harvester's Scythe: This is great if you've been stacking Lens-Maker's Glasses...es. Even if not, it's a sustaining effect, so that's nice.
Leeching Seed: Lower-risk but lower-reward version of the above without the 5% crit chance. Very useful.
Bandolier: Anybody can use this and you can benefit. It might be best to let them all stack on one character. These are great for refreshing your ult on a dime, letting you sustain yourself better in a fight. Later on, the ability to throw out multiple ults is a huge help.
Will-o'-the-wisp: Useful for the same reason as Gasoline, but noticeably stronger.
Average Priority Uncommons
AtG Missile Mk. 1, Ukulele, Kjaro's Band, Runald's Band: On-hit items. You don't do the most attacks, so these aren't the most important for you, but they're still good and worth grabbing.
Fuel Cell: If you have good equipment and are hoping to build an equipment-oriented build (Gesture, etc.), this is a good choice to get as many as you can.
Berzerker's Pauldron: Getting this to proc can be hard, but it's a nice buff when you land it. The explosive effects (Gasoline, Wisp) help a lot with this.
Infusion: I was tempted to put this in the low priority bracket, but you should probably still grab them -- they're just not your primary concern. You want a decently-contained health pool and would rather have defense than these.
Hopoo Feather, Wax Quail: Eh, why not. If you have no other options, go for it.
Red Whip: Being a speed item, this might sound like a big deal, but it's kind of... not, because you won't spend a lot of time out of combat.
Predatory Instincts: The buff is small unless you stack a lot of crits, and a lot of these as well.
Old War Stealthkit: Everybody could use one of these, but you probably want to choose other items first.
Low Priority Uncommons
Chronobauble: If you have no other options or it's a boss drop, sure, go for it; otherwise, this does not provide enough of a benefit to really be worth anything except as trade bait at the Bazaar.
Rose Buckler: Okay, so I said earlier that stacking defense would be better for you than health. So why is this, an item that provides armor, so low on the list? Simple: it's only active while you're sprinting, meaning that during most of the time when you'd want it, it won't do anything for you.
N'Kuhana's Opinion: Oh come on, you knew this would be up here. You heal all the time! This is probably your best item if you can get it.
High Priority Rares
Rejuvenation Rack: If you can get this and N'Kuhana's Opinion, you're pretty set. If not, this is still a great item to boost your sustain by a lot.
Brilliant Behemoth: See Gasoline and Will o' the Wisp. It's just that this procs on everything. Helps you kill groups much easier.
Brainstalks: As the game goes on, you'll face more elites, and this obviates the need for any Backup Mags.
Sentient Meat Hook: Since this pulls enemies toward the one the proc happened to, this is really good with your ult to suck more enemies in, or just to deal bonus hits to them.
Alien Head: Possibly an alternative to Backup Mags that will take some of the burden off of the rest of your team, especially if there's multiple characters dividing those up (if there's, say, just an Artificer, or you already have Brainstalks, leave this for them). Mostly, this lets you ult more often, which is extremely useful.
Average Priority Rares
Ceremonial Dagger: You kill a lot of things, so these are nice, but everyone benefits just as much from them. Notably, don't bother stacking them if you find them at a bazaar because they no longer shoot more daggers per stack.
Happiest Mask: It's okay, I guess. A sweetener, like most of this tier.
H3AD-5T v2: Remember in RoR1 when you could stack Headstompers to incredibly goofy results? It's a lot harder now. Unless you or someone on your team is building a specifically gimmicky build, these will probably go to whoever runs into them first, or maybe the Huntress, Mercenary or Artificer, who will appreciate the improved airtime. They also remove fall damage entirely, which is sweet.
57 Leaf Clover: Sure, why not.
Soulbound Catalyst: Goes great if you're doing an equipment-oriented build. Otherwise, you don't particularly need this.
Dio's Best Friend: Honestly, you'll probably want to give this to someone squishier, but you can still use this if nobody else grabs it first.
Hardlight Afterburner: This depends on your playstyle a lot. I don't use the shockwave a lot, so I don't consider the HLAB that big a deal on REX, but you might abuse the hell out of it, and thus want this for three charges on a four-second cooldown each.
Wake of Vultures: Although it's not bugged anymore like it was when it first came out (thus making it not a liability), I still have to fight the temptation to call this the "Wank of Vultures" constantly, because it's frankly not that useful. Nice sweetener, I guess.
Low Priority Rares
Unstable Tesla Coil: As someone who prefers to get in close with most characters, I love the UTC on everybody usually, but REX doesn't want to get close. So, let someone who gets in closer have this.
Frost Relic: Even with the buffs extending its range, the Frost Relic is not a good choice for you. This needs to go back to being an uncommon so you can reasonably stack them and do some silly things with it.
Equipment is in the Equipment section.
Get If You Want Or It Helps Your Build
Shaped Glass: High risk but high reward. This technically makes your skills cheaper by reducing your health pool, therefore reducing how much they can take, but you have less HP overall for other times, and REX aren't that tanky out of combat. It does add more healing to your M1 and more damage to your M2, though, so if you feel like taking the risk, do it.
Corpsebloom: Stored healing allows you to tank some big hits, in a way, with good timing. But moreover, any increased healing effect is nice, so this is basically Rejuvenation Rack but easier to grab, but it's not necessarily the greatest thing ever, since the downside can really shorten runs later on.
Gesture of the Drowned: REX are just as good at using equipment as anyone else. If you have a good attacking equipment and plenty of fuel cells, this is a worthwhile purchase.
Don't Pick Up
Brittle Crown: I avoid this item anyway, but THIS IS A RUN-KILLER. Self-damage triggers gold loss.
Transcendence: Despite what I'd heard, this doesn't make your M2 or ult unusable, but you pay out of your shield, and it doesn't seem like the cost goes down any. It also makes all your healing you've been stacking and that you have naturally completely worthless. This isn't quite the run-killer that the Brittle Crown is, but it's not a good idea to take it.
So, there's not really a lot of variance in terms of how good or bad equipment is for characters, but I will note that the Primordial Cube is extra-good for REX to set up ults, and that I like having the Gnarled Woodsprite for early phases for the bonus regeneration. When it comes to the Lunar Equipment, Hellfire Tincture is not recommended because of its small AoE around your body, and Spinel Tonic is, as with anyone else, most recommended if you can keep it up perpetually so you never feel the tonic sickness effect (good choice if you've stacked Fuel Cells and GoD, otherwise pass on it). Otherwise, use the same judgment on these that you do with other characters. Which is to say, don't bother.
Hopefully, this should give you a pretty good idea on how to play REX and let you strategize a little in advance of choosing them. REX aren't the most versatile character in the game, but they're one of the most useful with the right build. Poking around some other guides, I've seen a surprising amount of variance in build -- like, more than I'd even guessed when I first took REX for a test drive. So, by all means, play around with REX and see what works for you, because it will probably be different from what works for me.