Zaxara, the Exemplary is a mythic Legendary Creature — Nightmare Hydra card from Dominaria United Commander (DMC), collector number 176. Current market price: $2.01, TCGplayer market prices via Scryfall.
Deathtouch {T}: Add two mana of any one color. Whenever you cast a spell with {X} in its mana cost, create a 0/0 green Hydra creature token, then put X +1/+1 counters on it.