Here is the full list of all 27 Rogue Party achievements.
Defeat the Hammer Knight
Defeat the Unholy Helm
Defeat the Needle Knight
Defeat the Twisted Worm
Defeat the Magma Worm
Defeat the Berserker Golem
Defeat the Goblin King
Defeat the Wizard's Dagger
Score a redundant kill.
Defeat the Gorgon
Defeat the Horrific Skull
Defeat the Enormous Bat
Defeat the Enormous Worm
Score two redundant kills.
Score three redundant kills.
Kill the Yellow Demon
Kill the Brood Mother
Kill the Golem King
Kill the Abomination
Unlock the Wizard's body parts.
Score four redundant kills.
Score five redundant kills.
Score 10 redundant kills.
Score 15 redundant kills.
Score 20 redundant kills.
Score 25 redundant kills.
Score 30 redundant kills.