Tap Eater using the obtained activated ability from Phenax, milling your opponent for 4 cards.
If, after the mill, a creature card exists in any graveyard, pay ({0} magic symbol) and exile a creature card from a graveyard for Eater's activated ability to untap it.
Repeat until you've milled out your opponent or run out of creature cards in graveyards to exile.
Results
Mills your opponents' libraries out.
The combo depends on the number of creature cards in your opponents' collective graveyards.