At the beginning of your upkeep, sacrifice Molten-Tail Masticore unless you discard a card.

, Exile a creature card from your graveyard: Molten-Tail Masticore deals 4 damage to any target.

:
Regenerate Molten-Tail Masticore
(The next time this permanent would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.).