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