Chattergeists

Skulk, Possess (Whenever a creature with Possess attacks, you may remove it from combat. If you do, attach it to target creature defending player controls and it becomes an Aura Enchantment with "Enchanted creature gets -1/-1." It becomes a creature again when the enchanted creature leaves the battlefield.)
Whenever Chattergeists attacks, you may sacrifice it. If you do, create 3 1/1 black Shade creature tokens with Possess tapped and attacking.