Beledros Witherbloom - 282 M STX

Flying
At the beginning of each upkeep, create a 1/1 black and green Pest creature token with "When this token dies, you gain 1 life."
Pay 10 life: Untap all lands you control. Activate only once each turn.

mythic
Legendary Creature — Elder Dragon
From the Magic: The Gathering set Strixhaven: School of Mages.