The Battle Master fighter has access to a number of maneuvers that add a superiority die to the damage roll. For instance, the Trip Attack maneuver says (PHB, p. 74):
When you hit a creature with a weapon attack, you can expend one
superiority die to attempt to knock the target down. You add the
superiority die to the attack’s damage roll, and if the target is
Large or smaller, it must make a Strength saving throw. On a failed
save, you knock the target prone.
The Critical Hits rule states (PHB, p. 196):
When you score a critical hit, you get to roll extra dice for the
attack’s damage against the target. Roll all of the attack’s damage
dice twice and add them together. Then add any relevant modifiers as
normal. […] If the attack involves other damage dice, such as from
the rogue’s Sneak Attack feature, you roll those dice twice as well.
During our game, the fighter PC rolled a critical hit. He then wanted to use a superiority die to use the Trip Attack maneuver to trip the enemy. Based on the above rules, is the damage from the superiority die also doubled?
I'm assuming the answer is yes based on the last statement in the Critical Hits section, but I wanted to confirm.
Best Answer
Yes
"If the attack involves other damage dice" sounds like a pretty solid indicator that "Superiority Dice" would be multiplied, if a maneuver were used that adds the result as damage.
While not applicable to everybody, that sounds like an awesome way to add extra damage to multiply (not that superiority dice are really game-breaking for additional damage) after learning that an attack hit... but I'd allow it, regardless.