Witch-Maw Nephilim is a rare Creature — Nephilim card from Guildpact (GPT), collector number 138. Current market price: $1.32 (foil $12.80), TCGplayer market prices via Scryfall.
Whenever you cast a spell, you may put two +1/+1 counters on this creature. Whenever this creature attacks, it gains trample until end of turn if its power is 10 or greater.