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