Here is the full list of all 17 Knight Squad 2 achievements.
Obliterate 2500 opposing knights
Slay 7 knights in a very short succession
Destroy 2500 walls
Unlock a desert themed map
Unlock a special sword for one knight
Bring back a flag in Capture the Flag while in a Kamikaze state
Win a Battle Royale round while dead
Win a Crystal Rush game under 1 minute
Survive in a Gladiator zone for 1 full minute
Capture 3 grails in a single game
Bring back 20 souls in one go
Eliminate the head racer while in last position
Keep the Minigun for a full minute in Juggernaut
Own all the beacons simultaneously
Close a paint zone of 25 tiles
Score a goal while all of your opponents are frozen in place
Win a Payload game when the opponent team was meters away from winning