Tishana, Voice of Thunder is a mythic Legendary Creature — Merfolk Shaman card from The Lost Caverns of Ixalan Commander (LCC), collector number 291. Current market price: $0.38, TCGplayer market prices via Scryfall.
Tishana's power and toughness are each equal to the number of cards in your hand. You have no maximum hand size. When Tishana enters, draw a card for each creature you control.