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