Here is the full list of all 27 Rooks Keep achievements.
Kill 1000 enemies
Win 200 matches
Win in every Chess map
Turn your pawn into a queen in chess
Win each game-mode
Defeat the attacker in Combat Chess
Beat the AI at Classic Chess
Kill 10 enemies using Bash
Win a round without losing a life (LMS, TLMS)
Win in every arena map
Win a match as every character (arena modes)
Win 20 matches
Kill 10 characters in one life with the Damage
Eliminate all teams without changing sides (Conversion)
Become the Warlord
Kill 10 team members
Kill an enemy with your ability
Defeat an upgraded piece (5 skills at least) without your own upgrades
Defeat a Warlord
Fully purchase all skills
Kill 25 enemies without dying
Upgrade your character 10 times in the same life
Win a match
Win a Team-Match
Win a match with 5 mutators running
Kill 10 enemies without dying
Draw first blood