Tyvar the Bellicose is a mythic Legendary Creature — Elf Warrior card from March of the Machine: The Aftermath (MAT), collector number 227. Current market price: — (foil $40.34), TCGplayer market prices via Scryfall.
Whenever one or more Elves you control attack, they gain deathtouch until end of turn. Each creature you control has "Whenever a mana ability of this creature resolves, put a number of +1/+1 counters on it equal to the amount of mana this creature produced. This ability triggers only once each turn."