Chandra's Incinerator

• WWizards of the Coast2020-06-23
  Official Ruling
  In a multiplayer game, Chandra's Incinerator counts damage dealt to opponents who have lost the game.
• WWizards of the Coast2020-06-23
  Official Ruling
  Combat damage is the damage that's dealt automatically by attacking and blocking creatures. Any other damage is noncombat damage, even if it's dealt during a combat phase by an attacking or blocking creature.
• WWizards of the Coast2020-06-23
  Official Ruling
  Chandra's Incinerator counts all noncombat damage dealt to your opponents, not the difference in their life totals since the turn began. For example, if an opponent was dealt 5 noncombat damage but gained 3 life, Chandra's Incinerator still costs just .
• WWizards of the Coast2020-06-23
  Official Ruling
  The cost reduction applies only to generic mana in the cost of Chandra's Incinerator. It can't reduce the requirement.

Rulings via Scryfall