Does Holy Water deal damage on a failed attack roll?

Question

The text of Holy Water states:

As an action, you can splash the contents of this flask onto a creature within 5 feet of you or throw it up to 20 feet, shattering it on impact. In either case, make a ranged attack against a target creature, treating the holy water as an improvised weapon. If the target is a fiend or undead, it takes 2d6 radiant damage.

In using it as a thrown weapon, the steps are such:

1. make a ranged attack against a target creature as a improvised weapon, and
2. if the target is a fiend or undead, deal 2d6 radiant damage.

Step 2 doesn't specifically require that the ranged attack in Step 1 succeed, only that an attack roll is made.

Does this mean that Holy Water deals 2d6 radiant damage to undead and fiends even if the attack roll fails?

Answer 1

If the attack roll fails, it does no damage

As the description of Holy Water says, it is to be treated as an improvised ranged weapon, and will use the rules as applied to other improvised ranged weapons. If you miss on your attack roll, the target fiend/undead will take no damage. If there was some Area-of-Effect damage that the Holy Water dealt (as in the Ice Knife spell), then the item description would say so.

In short, the splashed/thrown Holy Water is an improvised ranged weapon. If you miss, it deals no damage. The separation of the clauses ("Step 1" and "Step 2") is simply to clarify that on a hit, the holy water will only damage fiends or undead. If you threw your vial of water at some elven ne'er-do-well, even on a hit, he would just end up getting a little bit wet.