@JeremyECrawford Is the extra damage from Hexblade's Curse supposed to apply to Eldritch Blast? If so, does it apply to every single beam or just one? It seems a bit overpowered.
— Poppamunz (@poppamunz) March 20, 2018
Hexblade's Curse grants a bonus to any damage roll you make against the cursed target. That's a damage roll of any sort, whether caused by a weapon, a spell, or something else. #DnD https://t.co/CFjLPDvEmj
— Jeremy Crawford (@JeremyECrawford) March 20, 2018
Does it apply to each damage dice or just the overall result
Every time you make an attack is a separate instance of rolling damage dice…so it applies to all that hit. It isn’t like Fireball or Disintegrate where you roll multiple damage die for a single attack roll, but a spell that grants you multiple attack rolls.
Pretty cut and dry.
I would also like to know if it applies to each damage dice or just the overall result
I’m just curious how it works with things like Divine Smite. Does it only apply to your overall damage roll, or to the damage roll of your weapon, and then the damage roll of the divine smite. At level 10, with charisma of 5 n proficiency of 4 (9 Pally, 1 hex) using a longsword and a 1st level divine smite against a cursed enemy. I’m either doing 1d8+5+4 + 2d8, or 1d8+5+4 + 2d8+4, n with Extra attack, that means I ‘m either getting a +8 on every turn, or a +16 on every turn.
Also,
I definitely don’t think it counts for every damage dice, or it’d be 1d8(+4)+5 + 2d8(+4+4), leading to (if I attacked undead or fiends with a 3rd level divine smite)
1d8+5+4d8+1d8+24 in a single attack, with extra attack bringing the overall damage against a single Hexblade Cursed Undead/Fiend enemy to 2d8+10+8d8+2d8+48! That’s a minium of 70 damage and a maxium of 154 damage!! at 10th level!
Rules on damage rolls makes it clear when it states that special abilities can grant a bonus to damage…it doesn’t consider those things to be a separate instance of making a damage roll, just part of the original damage roll. Divine Smite also says that the damage is dealt in addition, making the implication that the dice are part of a single damage roll. As such, you are correct in that it doesn’t count for every damage dice, because it is part of the original damage roll. As such your example would add your proficiency bonus once. An example of multiple instances of damage would be higher level casts of Eldritch Blast, which grant you multiple attacks, meaning you’d add it to the damage for each that hits since each is a separate instance of a damage roll.
It get’s weird for things like Magic Missile though…because the spell being used as intended means you just roll 1d4 + 1 and each missile does that much damage…meaning that if you had access to that spell and were using hexblade’s curse, you would add the proficiency bonus to that damage which would be 1d4 + 1 + prof for each missile which is quite strong to say the least, especially at level 1 since you’d at minimum be dealing 12 damage to your target at level 1 and at maximum 21 with a spell that auto-hits unless the target has shield.