1 Card and 2 Artifacts will guarantee this achievement for you.
Easy Setup for Defeating Cleo
Build
Pretty simple. Cleo has 40 Hull and 10 Shield. His cannon attacks deal a total of 42 damage on the first turn. Bring Peri and Max, and focus on getting a Parry card.
Your two artifacts to find are Piercer and Lightspeed Boot Disk. Apply the Buoyant effect from the Boot Disk artifact onto Parry.
Going into the Cleo fight, you will top-deck Parry, and one-shot Cleo with a piercing Parry.
Neither artifact is completely necessary because of how much Parry will carry the fight, but having all of these will guarantee a kill. The earlier the better, as he will eventually switch to firing a total of 11 seeker missiles at once, making any stalling extremely difficult.
you can also do a full card cycle build and use charged beam from riggs to 1 shot it
If you can’t get buoyant or piercer it’s worth taking cards that negate an opponent’s turn (Dizzy has EMP Charge and Drake has a similar one). I won by having a heavy card draw deck with some energy boosting cards/artifacts. I went for Parry B instead of A so that if I drew it before I was ready for a kill (or didn’t have 3 energy), I’d still be able to keep it in my hand.
Also had an easy run in the Ares ship.
Didn’t find the Lightspeed Boot Disk and my deck was big,
but I found the event that duplicates a card a bunch of times made drawing Parry way easier.
I used parry with Ares Cannon V2 and an extra energy artifact.
if you do somehow survive till the seeker missile phase, make sure to bring missile malware to turn the seeker missiles against cleo
I beat him without taking any damage with an infinite combo using Books and Riggs. This combo also cleared all fights once I discovered it.
Core cards for combo:
Crystal Shard + Magi-Battery + Draw Shot/Quick Thinking + Overflowing Power
Basically, thin your deck enough where you are always drawing Crystal Shards when you cycle your deck. I managed to do this by getting an early Jettison Hatch artifact. I don’t think Overflowing Power is necessary, but it sped the combo up.
“Unpolished Crystal A”, Books’ Grimoire artifact and Riggs’ Quickdraw artifact helped with turn 1 consistency. I also had Riggs’ Flywheel artifact which helped.
I managed to beat him by using the card that makes whatever part you shoot brittle, then using parry on it. Got lucky with my card draw and dealt a crisp 84 damage on the very first turn, killing him instantly.
What are the rewards for this fight?
You get an artifact that gives you 1 energy per turn.
That should work! I did something similar to this yesterday on my first time with the Ares ship. Drew a Parry and Extra Battery cards in my first hand, turned on the second cannon, and it was over immediately. It was definitely a “wow did that just happen?” moment