Does the special thrown attack of a Hammer of Thunderbolts deal damage?

Question

The Hammer of Thunderbolts has a special thrown property:

The hammer also has 5 charges. While attuned to it, you can expend 1 charge and make a ranged weapon attack with the hammer, hurling it as if it had the thrown property with a normal range of 20 feet and a long range of 60 feet. If the attack hits, the hammer unleashes a thunderclap audible out to 300 feet. The target and every creature within 30 feet of it must succeed on a DC 17 Constitution saving throw or be stunned until the end of your next turn. The hammer regains 1d4 + 1 expended charges daily at dawn.

I suspect it is probably the case, but just to be sure:
Does the special thrown attack of a Hammer of Thunderbolts deal damage, in addition to its stated effect? (2d6+1 + Strength modifier + other bonuses if any)

Answer 1

In the Making an Attack section of the Player's Handbook (p. 194) the process for making an attack is as follows (emphasis mine):

1. Choose a target. Pick a target within your attack's range: a creature, an object, or a location.
2. Determine modifiers. The DM determines whether the target has cover and whether you have advantage or disadvantage against the target. In addition, spells, special abilities. and other effects can apply penalties or bonuses to your attack roll.
3. Resolve the attack. You make the attack roll. On a hit, you roll damage, unless the particular attack has rules that specify otherwise. Some attacks cause special effects in addition to or instead of damage.

Since the the Hammer of Thunderbolts doesn't specify that its thunderclap replaces the weapon damage, the thrown attack does regular damage in addition to the thunderclap effect.

Answer 2

Yes it does.

Ranged Weapon Attacks Do Damage

The item decription reads (emphasis mine):

While attuned to it, you can expend 1 charge and make a ranged weapon attack with the hammer, hurling it as if it had the thrown property with a normal range of 20 feet and a long range of 60 feet.

If you weren't attuned to it, and threw it as an improvised weapon, it would deal normal damage. So, logic would dictate that if managed to hit you by beating your armor class it when thrown as if it had the thrown property would deal normal bludgeoning damage. Using the thrown property, throwing a hammer for a ranged weapon attack would deal normal damage.

D&D Doesn't have Meaningless Rolls

By the reading that it doesn't do normal damage the effect requires both an attack roll and a saving throw. There isn't any effect in the game that requires both a attack roll and a saving throw for imparting one source of damage. This would be so out of place as to be and feel broken.

If they wanted it just to be a rare occurrence, they could have just set a easier to beat DC. They didn't, meaning the attack roll is there for something -- which would be a thrown weapon attack as the item said, and that attack would be really odd logically if getting hit by a maul of that size didn't cause you to suffer harm.

Common Language of Trigger

Then we have the way it is written. This is pretty common language for the trigger of an special effects.

If the attack hits, the hammer unleashes a thunderclap audible out to 300 feet. The target and every creature within 30 feet of it must succeed on a DC 17 Constitution saving throw or be stunned until the end of your next turn.

If the (normal thrown weapon) attack hits (before it is finished resolved by dealing hammer damage), it releases a thunder clap. Compare this language to say hunters mark or thunderous smite which read

... whenever you hit it with a weapon attack...

and

... you hit with a melee weapon attack during this spell’s duration, your weapon rings with thunder that is audible within 300 feet of you...

respectively. No one argues that the normal attacks of these spells don't do their normal damage. Just that the special effect of the spell (or magic weapon) is triggered when the attack lands.

"extra damage"

In comments it was brought up that the effects of the smite spells and hunters mark was "extra damage". Which is true, that is their effect. That said, the effects of the hammer are more like the push effect part of Thunderous smite, requiring a save after the attack lands.

However, Repelling Blast Eldritch Invocation is great example that doesn't have extra or additional damage effects which makes the effect more clear (emphasis mine):

When you hit a creature with eldritch blast, you can push the creature up to 10 feet away from you in a straight line.

This doesn't negate the damage of eldritch blast or the Agonizing Blast Eldritch Invocation. The same is true for stunning strike:

When you hit another creature with a melee weapon attack, you can spend 1 ki point to attempt a stunning strike. The target must succeed on a Constitution saving throw or be Stunned until the end of your next turn.

And the Battle Master Fighter's Disarming Attack:

When you hit a creature with a weapon attack, you can expend one superiority die to attempt to disarm the target, forcing it to drop one item of your choice that it's holding. You add the superiority die to the attack's damage roll, and the target must make a Strength saving throw. On a failed save, it drops the object you choose. The object lands at its feet.

Which makes it the clearest that the rules expect the hit to already be dealing damage.

Answer 3

It does not

The mechanics of the Hammer of Thunderbolts are clear in when, how, and what happens when you want to use it's special ability.

The hammer's throwing mechanic is clear on that it gives you an option to make a ranged attack and then it is clear on how to handle the success of that hit. It does not include language that suggests that those effects are in addition to the standard damage. It just says "You can do X, and Y is what happens when X is successful."

When can you use it?

The hammer also has 5 charges. While attuned to it, you can expend 1 charge and make a ranged weapon attack with the hammer..

How do you use it?

hurling it as if it had the thrown property with a normal range of 20 feet and a long range of 60 feet.

What happens when you hit with it?

If the attack hits, the hammer unleashes a thunderclap audible out to 300 feet. The target and every creature within 30 feet of it must succeed on a DC 17 Constitution saving throw or be stunned until the end of your next turn.

Nowhere does it state that this special attack deals damage. It says that you can do it, and if you want to, you expend a charge, roll to hit, and if successful, then the target(s) make a DC 17 Con save for be stunned until end of your next turn.

Compare the wording here against other game effects

Javelin of Lightning

The Javelin specifically states to provide the standard damage in addition to the special properties whereas the Hammer does not(emphasis mine):

Each creature in the line excluding you and the target must make a DC 13 Dexterity saving throw, taking 4d6 lightning damage on a failed save, and half as much damage on a successful one. Make a ranged weapon attack against the target. On a hit, the target takes damage from the javelin plus 4d6 lightning damage.

Thunderous Smite

The spell thunderous smite also provides some direct evidence that the original attack damage is still included. See below (my emphasis):

The first time you hit with a melee weapon attack during this spell’s duration, your weapon rings with thunder that is audible within 300 feet of you, and the attack deals an extra 2d6 thunder damage to the target. Additionally, if the target is a creature, it must succeed on a Strength saving throw or be pushed 10 feet away from you and knocked prone.

The Hammer doesn't use any of that language that refers to the original damage values.

Contagion

Contagion is a touch spell attack that requires an attack roll that has no direct damage. It gives a condition in the same way the hammer gives a condition. It's a touch, but it's an melee attack roll which could also be considered an unarmed strike.

However, the effects of that touch are to force an ongoing save. Much in the same way that Hammer doesn't do damage, it forces a save.

But it's not a big deal if you provide the damage

At the end of the day, there are some real weird attributes to this weapon. While it can give you a big boost to your STR (depending on which Belt you've got), it's got some serious problems with it - especially with regard to the thrown feature.

• It's still just a +1 magic weapon, which isn't that big of a deal at higher levels (but that potential extra +5 from your STR above 20 is a big deal.)
• The Stunned save affects every creature within 30' of the target. Including Friendlies.
• If you throw it in regular range, you are in the area of effect and have to make the save against being stunned.
• Once you throw it, the weapon is now however far away you through it. It doesn't come back.
• The damage will be 2d6+STR+Proficiency. For the level you are currently at, that's not huge and is unlikely to sway a fight. Especially with the issues listed above when you use it.