Gisela, Blade of Goldnight changes damage exchanges across the battlefield. Damage to opponents and their permanents is doubled, while damage to you and your permanents is reduced by half, rounded up. Flying and first strike make Gisela a meaningful attacker and blocker, but the larger attraction is how she improves both offensive and defensive damage for a red-white deck.
Purphoros, God of the Forge and other repeatable damage sources become more threatening while Gisela is present. Token armies can also deal much more combat damage, and the prevention effect helps your creatures survive opposing burn or combat. Unlike a multiplier limited to your own sources, Gisela can increase damage opponents deal to each other, changing the value of combat around the table.
The prevention and doubling apply to damage, not every change in life total. A life-loss effect such as Exsanguinate is not doubled or reduced by these abilities. Damage that cannot be prevented also interacts differently with the defensive half, so the precise wording of the opposing effect matters when calculating whether you or a creature will survive.
Seven mana makes Gisela a substantial commitment. Reanimation in a deck with black, or a strong ramp package, can help deploy her while preserving resources for protection. Her best turns occur when an existing board or damage spell can immediately exploit the multiplier, while her defensive effect gives you more room to survive the response if the game continues.
