This is someone who has played this game casually explaining the characters, relics, cards. I will also provide helpful tips and possible archetypes of the decks.
Don't rush in haphazardly!
This game is not about battles that are impossibly hard, that's held for the final area's bosses, it's a game of attrition. You have to do battle upon battle upon battle where your resources are slowly whittled down to a stump. Focus on blocking more than attacking unless you're fighting Thieves or other enemies that have time limits before your or your wallet's anticlimactic demise. You generally want more defense than offense in your deck.
Don't be afraid to use potions!
All in the name of attrition, use your potions when they make the battle go more quickly or when they might save you some damage. This is a trap I sometimes fall into where I want to save the potions till later and that is the cause of your death.
Do not just write off a card at a first glance!
Cards are your everything in this game, quite obviously, but sometimes it's hard to tell if a card will be good. So I entrust you to do this simple exercise, look at the new card, look at the nearest equivalent, Strike or Defend, and see if it's any good. Most of the time, the new card will beat the equivalent.
Don't be afraid to ditch cards!
There are two parts to this, first part is those card rewards you get after every battle: if all of them do not fit your deck's archetype or are just bad, put the cards back into the booster pack and give them back to the cashier, demanding a refund (your deck will thank you). Second, after you start ramping into late game, don't be afraid to dump ineffective or weak cards, Strikes are the primary target as you start to get better and better offense cards and need to keep your decks lean.
We will begin this guide with the only part of the game that can be safely snipped away from the rest without needing to drag stuff with, the potions. Potions are a valuable tool in this game and your usage of them is paramount, as they can save you if used properly.
First off, potions are always a positive in this game for the most part with one exception, even if you misuse them, you will either not affect the battlefield at all or provide yourself a small benefit. I will list them off in random order.
- Elixir - Probably the weakest potion of the bunch, removing curse and status cards from your hand. The most niche card with very few enemies able to effectively fill your deck with garbage. It also has the least immediate effect on the battlefield.
- Draw Potion - One of the strongest potions you could possibly get, it's possible to turn the entire battle around with this thing if you get lucky enough, though it has its unfortunate downside if used poorly. If you use it without any energy, you're rolling the dice to see what cards you get rid of for the most part, this can be good and it can be bad with what cards it gets rid of. If you are effectively managing your cards, however, it's more bad than good.
- Fire Potion - A really good potion for bosses or strong single enemies, 20 flat damage is not bad.
- Explosive Potion - The sibling to the Fire Potion, worse than the Fire Potion for single enemies but good for groups. 10 damage among all enemies is not bad.
- Poison Potion - 6 flat poison onto an enemy, a delayed damage worth of 6+5+4+3+2+1=21. More effective on The Silent due to the fact poison is much stronger when stacked as it has more numbers to go through.
- Protection Potion - 12 block for just popping this sucker, really good in a pinch when you're about to die.
- Regen Potion - The hardest potion to use effectively, best used for easy encounters so you can get a net positive HP regain or hard encounters where the healing just acts as a +3 block every turn. Heals 3 HP per turn for 5 turns.
- Dex/Str Potions - Grouping these two together because they're basically the same thing for different stats, +2 Dex or +2 Str, really good. I would say the Dex potion is better due to the account that blocking is very important.
- Weak Potion - One of the potions on the less impactful side, certainly helps in keeping your sorry self alive, three turns of weak on the enemy is good. Sadly, Weak is the one status ailment that gets stuff like this that ailments like Vulnerability or Frail would really like. In fact, a potion of Frail would be the only way to get it yourself for this game.
- Energy Potion - One of the better potions if you know what you're doing, two extra energy for the turn is really potent, especially with the Draw potion.
Relics are a much stronger tool in this game compared to potions. Relics also happen to have a greater variety of effects to choose from.
- Burning Blood - Gain 6 HP at the end of the battle, Ironclad only. I believe this is better than The Silent's starting relic due to the fact that it only provides positive or nothing. It's really good at keeping you alive and is useful for taking more battles.
- Ring of the Snake - At the start of combat, draw two cards, The Silent only. It's good for providing you more options at the start, but if a good amount of your amazing cards are in the start of your hand when you don't have the energy to use, they are shown an early grave into the discard pile. Really good if you get extra energy on the start of your turn.
- Snecko Skull - Whenever poison is applied, apply another stack of poison. Best common relic for The Silent as it makes his poison runs much stronger, especially when you have Noxious Fumes, basically making it Noxious Fumes+ or Noxious Fumes++ if you've already upgraded it.
- Anchor - Start combat with 10 block. Same thing with the Ironclad's Burning Blood, at worst, neutral; at best, useful.
- Ancient Tea Set - After going to a campfire, you have two extra energy for the start of your first turn for the next enemy encounter. Really good relic for the fact it's a 100% use for the bosses, also makes Ring of the Snake much better.
- Art of War - If you go a turn without playing attacks, gain one extra energy next turn. It's really good for The Silent as his win conditions are more varied than hitting someone in the face. Unfortunately, The Ironclad cannot make as much use of this due to the fact he is restricted to that win condition.
- Bag of Marbles - Give one Vulnerable to all enemies. A really potent start to your combat encounter, especially if you have an offensive starting hand.
- Bag of Preparation - Literal copycat of Ring of the Snake, read above for my thoughts.
- Blood Vial - Gain 2 HP at the start of combat. Useful if not very potent, its real viability comes in the vampire event where, instead of sacrificing max HP, you sacrifice it for the Bites.
- Bronze Scales - Enemies attacking you take three damage. Good for a defensive run, but will not win it for you.
- Dream Catcher - Resting at a bonfire lets you get new cards. Healing AND getting new cards!? Sign me up!
- Frozen Egg - Upgrade a Power once you pick it up. Probably one of the best Egg relics you can get due to the fact that powers are extremely powerful cards.
- Happy Flower - Every third turn, gain an extra energy. What can I say? Really strong.
- Juzu Bracelet - Prevents enemy encounters from mystery spaces. Really good at keeping you alive if you spam mystery spaces.
- Lantern - Gives you one energy for your first turn. Really good with Ring of the Snake.
- Molten/Toxic Egg - Upgrades an attack/skill on pick up. Basic.
- Oddly Smooth Stone/Vajra - Grants 1 Dex/Str at the start of the combat.
- Omamori - Absorbs the next two curses you take. Lets you take some curse risks you might not have taken before.
- Orichalcum - Grants 6 block at the end of your turn if you don't have. Good for if the RNG prevents you from getting block cards. Kind of says something about the items when the fated material used in most RPGs is a COMMON relic.
- Pen Nib - On every tenth attack, deal double damage. Basic if needing good planning.
- Prayer Wheel - Non-boss chests contain cards. More cards.
- Regal Pillow - Heals an additional 15 HP when resting at a bonfire. Probably best that it's a static amount as having it be a percentage can make it too weak or too strong.
- Singing Bowl - Increases max HP by 2 if you skip a card reward. Further rewarding you for keeping your decks trim.
- Strawberry - Increases max HP by 7.
- Tiny Chest - Increases current gold by 30%, makes chests appear 10% more in mystery rooms. Even better with Juzu Bracelet.
- War Paint/Whetstone - Randomly upgrades 2 skills/attacks. Basic, best gotten later on.