Karnax's Eternal Hunger

At the beginning of your upkeep Karnax's Eternal Hunger deals 3 damage to target creature or player and you gain 3 life.
Repeat this effect if you control a Planeswalker named Tirik, Lord of the Plague, Aerra, Corrupted Animist, or Kojak, fire of Karnax. Repeat this effect twice if you control a creature named Karnax, the Devourer.