Here is the full list of all 42 Alina of the Arena achievements.
Complete a run as a Mercenary
Complete a run as a Pyromancer
Defeat the Demon of the Arena
Complete a run as a Bandit
Throw a rock more than 5 times in a fight
Perform a 12 hit combo
Encounter every type of enemy
Play more than 16 cards in a single turn
Win a fight with 1 HP left
Complete a run as a Warrior
Conquer the Royal Arena
Gain more than 25 Strength in a fight
Receive more than 25 Fatigue in a fight
Unlock all cards
Unlock all accessory slots
Kill 3 enemies in a single attack
Unlock all item slots
Conquer the Underground Arena
Defeat a champion without taking any damage
Immobilize a single target more than 3 times in a fight
Conquer the Slave Arena
Stun a single target more than 5 times in a fight
Complete a run as a Slave
Complete a run as a Hunter
Complete a run as a Samurai
Complete a run as a Deprived
Complete a run in Hardcore Mode
Stack more than 30 Bleed on a single target
Gain more than 100 Focus in a fight
Gain more than 200 Block in a fight
Stack more than 200 Burn on a single target
Deal more than 300 damage in a single attack
Kill 6 enemies in a single turn
Upgrade one weapon 5 times
Possess more than 2000 gold
Have more than 5 different Statuses in your deck
Complete a run with at least one cursed weapon equipped
Complete a run without equipping any accessories
Complete a run under 40 minutes
Defeat a champion in 3 turns
Hurl a Gemstone
Unlock all achievements