Depthdelver Missionary

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
For every three cards exiled by Depthdelver Missionary's delve ability, populate. (Put a token onto the battlefield that's a copy of a creature token
you control.)
"I carry Selesnya's message into the sewers and catacombs - the places where her wisdom is
needed the most."