Unearthed Arcana Kiss of Mephistopheles: Unbalancing?

[jayoungr]

A warlock player in one of my games wants to take the "Kiss of Mephistopheles" invocation from Unearthed Arcana. The character's pact is Great Old One rather than Fiend, but we've reflavored GOO to fit the setting, and the character meets all the other prerequisites. However, I'm concerned that giving the character fireball (and as a bonus action at that) may be too powerful. The party is level 6 with six PCs: warlock, fighter, rogue, barbarian, support-specced bard, and shaman (custom class).

For reference:

Kiss of Mephistopheles
Prerequisite: 5th level, the Fiend patron, eldritch blast cantrip
You can channel the fires of Mephistopheles through your eldritch blast. When you hit a creature with that cantrip, you can cast fireball as a bonus action using a warlock spell slot. However, the spell must be centered on a creature you hit with eldritch blast.

https://media.wizards.com/2017/dnd/downloads/20170213_Wizrd_Wrlck_UAv2_i48nf.pdf

What are people's thoughts? Is it too powerful, or am I just worrying too much? Is there anything I should watch out for if I do allow it? Does it interact strangely with the Great Old One pact?

Also, I assume that eldritch blast does its normal damage in addition to the damage of the fireball? And the fireball is non-shapeable, i.e. allies could get caught in it?

 

[Worrgrendel]

It’s not really any different than a Sorcerer casting a cantrip and Quicken Fireball. More restrictive really since it MUST be centered on the target.

 

[abirdcall]

Isn't worth the invocation to me. It's an investment into fireball which is not always the best choice for the spell slot. When it is, you're just getting 2 attacks on it. Additionally, the constraint on the fireball will make it worse as it can't be placed between creatures or behind or to the side to avoid hitting party members.

I might take it for levels 5 for the novelty of it. It becomes even worse at 7+.

 

[Tessarael]

Thinking about it, getting Eldritch Blast and Fireball off on the same target in the same round does seem too powerful to me, and I'm playing a Warlock with A5E. That would have pushed my damage in a round much higher with the 8d6 5E D&D Fireball.

It is not unbalanced to allow Warlock access to the Fireball spell. I just wouldn't allow it in combo with Eldritch Blast in the same round, unless you're say multi-classed to Sorcerer and using the Quickened Spell metamagic, which has a significant cost to do so.

 

[Charlaquin]

Well a Fiendlock that qualifies for the feat already has access to fireball, and being able to cast it and Eldritch Blast in the same turn is not an unreasonable use of an invocation. The one thing I see as potentially abusable about it is that it extends the range at which you can cast fireball, especially combined with eldritch spear. But if you don’t usually have engagements where that extra range would be relevant then it seems perfectly fair.

 

[Tessarael]

It’s not really any different than a Sorcerer casting a cantrip and Quicken Fireball. More restrictive really since it MUST be centered on the target.

To achieve that, you need one of these options:

• Sorcerer level 5 with the Magic Initiate or Spell Sniper feat to get the Eldritch Blast cantrip
• Warlock with the Metamagic Adept feat and some way to get the Fireball spell
• Warlock X/Sorcerer 3
• Warlock 1/Sorcerer 5

Most of these are quite viable, but they do have a significant opportunity cost to achieve them.

 

[Sorcerers Apprentice]

To achieve that, you need one of these options:

• Sorcerer level 5 with the Magic Initiate or Spell Sniper feat to get the Eldritch Blast cantrip
• Warlock with the Metamagic Adept feat and some way to get the Fireball spell
• Warlock X/Sorcerer 3
• Warlock 1/Sorcerer 5

Most of these are quite viable, but they do have a significant opportunity cost to achieve them.

But they also allow a whole bunch of other shenanigans, while Kiss of Mephistopheles only lets you do this one combo.

I don't think it's a particularly strong invocation, the extra damage from hitting a target with Eldritch Blast will often be offset by less than ideal placement of the Fireball. And past lvl 9 Warlocks aren't going to want to spend slots on Fireball anyway, when Synaptic Static is available.

 

[Seramus]

It's a neat bit of tech since it gives the GOO access to fireball without having previously known it, but a Warlock who is using his spell slots for damage isn't going to rock any boats on the power scale. I would allow it, if you are giving other players the same opportunities to nudge the rules like you are doing for this player.

 

[DrJawaPhD]

What are people's thoughts? Is it too powerful, or am I just worrying too much? Is there anything I should watch out for if I do allow it? Does it interact strangely with the Great Old One pact?

The UA you linked was #29. The more recent UA #40 revised Kiss of Mephistopheles to not require Fiend patron. So if you want to allow UA then I wouldn't worry about the interaction with Great Old One, since it is legal in the most recent UA "Rules As Written"

https://media.wizards.com/2017/dnd/downloads/June5UA_RevisedClassOptv1.pdf

 

[Stormonu]

It's pretty subpar.

1) You have to use an action to cast Eldritch Blast
2) You have to hit
3) You have to spend a bonus action
4) You have to spend a warlock spell slot
5) The target(s) get a save against the fireball