Genghis Frog is a uncommon Legendary Creature — Frog Mutant Rogue card from Teenage Mutant Ninja Turtles (TMT), collector number 148. Current market price: $0.28 (foil $0.24), TCGplayer market prices via Scryfall.
Trample Whenever Genghis Frog or another Mutant you control enters, create a Mutagen token. (It's an artifact with "{1}, {T}, Sacrifice this token: Put a +1/+1 counter on target creature. Activate only as a sorcery.")