Muck Mage

Deathtouch, hexproof
When Muck Mage enters the battlefield, you may
search your library for a card named Aetheric
Waste, reveal it, put it into your hand, then
shuffle your library.
Whenever you cast a spell named Aetheric Waste
for its flashback cost, you may cast a card named
Aetheric Waste from your graveyard without
paying its mana cost, then exile it after.