So even though I play D&D a lot, I still suck at math, and I have a future combat that uses Undead Fortitude quite a Lot Undead Fortitude : If damage reduces the zombie to 0 Hit Points , it must make a Constitution saving throw with a DC of 5+the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie drops to 1 hit point instead. Therefore, is there an easy macro that can take the last damage taken and run the saving throw automatically?