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