Here is the full list of all 15 Invasion: Brain Craving achievements.
Defeated 150 Unholy Dead!
Defeated 100 Unholy Dead!
Awoooo! Awoooo! Defeated the Werecar miniboss.
Recruited Blue. Ga-ry, Ga-ry, Ga-ry!
Recruited Peach. She was in this castle all along, hero.
Recruited Jeth.
Recruited Doc Brown. Now if only we could go back in time!
Defeated 50 Unholy Dead!
Recruited Aisha.
Recruited Clarissa.
Defeated 10 Unholy Dead!
Recruited Red. .... ..... ....... ....
Rerolled your game!
Defeated your first Unholy Dead!
Enter Post-Apocalyptia