Magmasaur is a rare Creature — Elemental Dinosaur card from Tempest (TMP), collector number 188. Current market price: $0.38, TCGplayer market prices via Scryfall.
This creature enters with five +1/+1 counters on it. At the beginning of your upkeep, you may remove a +1/+1 counter from this creature. If you don't, sacrifice this creature and it deals damage equal to the number of +1/+1 counters on it to each creature without flying and each player.