Full list of all 46 Slay The Spire achievements worth 1,070 gamerscore. It takes around 150-200 hours to unlock all of the achievements in the base game.
The base game contains 44 achievements worth 1,000 Gamerscore, and there is 1 DLC pack containing 2 achievements worth 70 Gamerscore.
Win a battle with 1 HP remaining.
Defeated the Slime Boss.
Defeated Hexaghost.
Defeated the Guardian.
Complete Ascension Level 20.
Beat the game with a deck containing no uncommons or rares.
Beat the game with a single relic.
Have 25 or more Focus during combat.
Channel 9 Plasma in a single turn.
Complete the Ending with the Ironclad, Silent, and Defect.
Beat the game with a 5 card deck or smaller.
Complete the Ending with the Defect.
Complete the Ending with the Silent.
Complete the Ending with the Ironclad.
Defeat the Transient before it fades away.
Beat the game in under 20 minutes.
Finish Donu with a Feed.
Complete Ascension Level 10.
Defeat a boss on turn 1.
Have 999 Block during combat.
Play 10 Shivs in a single turn.
Play 25 cards in a single turn.
Have 50 or more Strength during combat.
Win a Daily Climb.
Have 3 or fewer cards in hand, draw, and discard pile combined.
Have 10 or more buffs during combat.
Beat the game with the Defect.
Have 99 or more Block during combat.
Apply 99 or more Poison on a single enemy.
Win a combat without playing an Attack.
Beat the game with the Silent.
Defeated the Time Eater.
Defeated the Awakened One.
Defeated Donu & Deca.
Defeat a boss without taking any damage.
Beat the game with the Ironclad.
Unlock Ascension mode.
Have 9 Energy during a single turn of combat.
Exhaust 20 cards in a single combat.
Defeat 3 enemies with Poison in a single combat.
Defeated the Collector.
Defeated the Bronze Automaton.
Defeated the Champ.
Obtain all other Achievements
Beat the game with the Watcher
Complete the Ending with the Watcher