Full list of all 101 Skul: The Hero Slayer achievements.
The base game contains 57 achievements, and there are 5 DLC packs containing 44 achievements.
Defeat the First Hero without saving the stage NPC
Keep talking to Headless
Die from a trap
Reach the top of the chandelier in the Demon King Castle
Play on Rookie Mode
Defeat the First Hero without getting hit
Acquire Warlord
Acquire Soul Knight
Acquire Defender Captain
Defeat the Leiana Sisters without getting hit
Stay in the black market for 5 minutes
Acquire Royal Guard Captain
Defeat St. Joan II without getting hit
Restore the Demon King Castle to its original form
Acquire Magnifico
Acquire Destroyer
Acquire Nightmare
Acquire Eternal Werewolf
Acquire Dark Avenger
Acquire Poseidon
Defeat the First Hero as Little Bone
Rescue the Demon King and return to the Demon King Castle
Defeat the Sword of Carleon, the First Hero
Acquire Demolitions Expert
Acquire Neo Samurai
Acquire Devil Berserker
Acquire Elder Ent Skull
Acquire Vanguard Captain
Acquire Ghoooooul
Acquire Carleon Commander
Acquire Gold Gargoyle
Acquire Minotaurus III
Acquire Eternal Mummy
Acquire Sniper
Acquire Master Ninja
Acquire Abyssal Monarch
Defeat Chimaera without getting hit
Acquire Frozen Spirit
Defeat the archbishop of the Leonia Order, St. Joan II
Acquire Dark Alchemist
Kill 100 adventurers
Acquire Super Rock Star
Acquire Joker
Acquire Desperado
Defeat the distorted goddess, Chimaera
Defeat Yggdrasil without getting hit
Acquire Arch Lich
Acquire Yaksha
Acquire Champion
Keep restocking from the collector
Defeat the adjutants of the Gold Mane Knights, the Leiana Sisters
Acquire Gambler
Acquire Grim Reaper
Defeat the elder ent, Yggdrasil
Reach the top of the throne in the Demon King Castle
Stay in the black market for 1 minute
Return after experiencing death