Sothera, the Supervoid
Whenever a creature you control dies, each opponent chooses a creature they control and exiles it.
At the beginning of your end step, if a player controls no creatures, sacrifice Sothera, then put a creature card exiled with it onto the battlefield under your control with two additional +1/+1 counters on it.
Disclaimer: This is a custom-made MTG proxy card and not tournament-legal.