In Fire Emblem 3 Houses, the final boss of the Azure route has 199 HP and is standing on a 60 HP heal tile. If you deal 3 damage, it goes to 196. 196+60=256.

In Fire Emblem 3 Houses, the final boss of the Azure route has 199 HP and is standing on a 60 HP heal tile. If you deal 3 damage, it goes to 196. 196+60=256. This overflows to zero and you win.