Trostani's Summoner is a uncommon Creature — Elf Shaman card from Dragon's Maze Promos (PDGM), collector number 110. Current market price: $0.39, TCGplayer market prices via Scryfall.
When this creature enters, create a 2/2 white Knight creature token with vigilance, a 3/3 green Centaur creature token, and a 4/4 green Rhino creature token with trample.