Here is the full list of all 15 Riddled Corpses achievements.
Achieve level 130!
You've finished all stages on arcade mode
Erika now has max power. Now kill the undead!
Fael now has max power. Now kill the undead!
You killed the fifth boss and finished stage 5!
Lieri now has max power. Now kill the undead!
Jon now has max power. Now kill the undead!
You killed the forth boss and finished stage 4!
Kill 50000 enemies in survival or arcade mode
You killed the third boss and finished stage 3!
You killed the second boss and finished stage 2!
Cloe now has max power. Now kill the undead!
Get 5 special items
You killed the first boss and finished stage 1
Your first death