Murktide Regent is a mythic Creature — Dragon card from Secret Lair Drop (SLD), collector number 1878. Current market price: $15.94, TCGplayer market prices via Scryfall.
Delve (Each card you exile from your graveyard while casting this spell pays for {1}.) Flying This creature enters with a +1/+1 counter on it for each instant and sorcery card exiled with it. Whenever an instant or sorcery card leaves your graveyard, put a +1/+1 counter on this creature.