Cruel Celebrant

• WWizards of the Coast2019-05-03
  Official Ruling
  If Cruel Celebrant dies at the same time as one or more other creatures and/or planeswalkers you control, its ability triggers for each of them.
• WWizards of the Coast2019-05-03
  Official Ruling
  In a Two-Headed Giant game, Cruel Celebrant's ability causes the opposing team to lose 2 life and you gain 1 life.
• WWizards of the Coast2019-05-03
  Official Ruling
  If a planeswalker that's also a creature dies, Cruel Celebrant's ability triggers only once.

Rulings via Scryfall