Stronghold Furnace

The controller of a face-up plane card is the player designated as the "planar controller." Normally, the planar controller is whoever the active player is. However, if the current planar controller would leave the game, instead the next player in turn order that wouldn't leave the game becomes the planar controller, then the old planar controller leaves the game. The new planar controller retains that designation until they leave the game or a different player becomes the active player, whichever comes first.

Stronghold Furnace's first ability interacts with all damage, not just combat damage. Notably, it doubles the damage from its own chaos ability.

If an ability of a plane refers to "you," it's referring to whoever the plane's controller is at the time, not to the player that started the game with that plane card in their deck. Many abilities of plane cards affect all players, while many others affect only the planar controller, so read each ability carefully.

If a spell or ability divides damage among multiple recipients (such as Pyrotechnics does), the damage is divided before Stronghold Furnace's effect doubles it. The same is true for combat damage.