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