I'm back with another homebrewed thing. But, I can't decide on a reasonable cost for it. See below:
Sharpened Spell
You spend X Sorcery Points. You modify a spell with a range that
is not Self or Touch, has a casting time of 1 action, and a duration
of Instantaneous.The spell you cast changes in the following ways:
- If the spell forces a save DC, roll a spell attack instead. You deal 0 damage on a miss. If you hit, multiply the damage dealt by 1.25
- If the spell is not single target, it becomes a single target spell. If the spell has area effects, it only affects the single target of
the spell. If it also deals damage, multiply the damage by 1.5
The idea is to maximize the damage dealt by turning your normal spell into an attack spell against a single target — basically trying to turn every spell into Disintegrate.
Justification of 50% Damage Boost
So that people don't pass too quick a judgement off this as possibly "too powerful" or "too weak," I'd like to break down the numbers here.
I based the 50% damage increase off of the One Target vs Multiple Targets table in the DMG.
DMG pg. 284
Spell Damage
Spell Level One Target Multiple Targets Cantrip 1d10 1d6 1st 2d10 2d6 2nd 3d10 4d6 3rd 5d10 6d6 4th 6d10 7d6 5th 8d10 8d6 6th 10d10 11d6 7th 11d10 12d6 8th 12d10 13d6 9th 15d10 14d6
The DMG says you can create a new spell with damage appropriate for its level by keeping the mean value of its damage around the same as the mean values of the dice shown in the Spell Damage table.
DMG pg. 283
Spell Damage
You can use different damage dice than the ones in the table, provided
that the average result is about the same. Doing so can add a little
variety to the spell. For example, you could change a cantrip's damage
from 1d10 (average 5.5) to 2d4 (average 5), reducing the maximum
damage and making an average result more likely.
On average, the mean values for single target spells according to that table is 50% higher than multiple target spells, so to compensate for the fact that this spell forces a multi-target spell to become a single-target one, the damage is scaled up by that amount.
Justification of 25% Damage Boost
If saving from a spell successfully causes you to take half damage, then its maximum possible damage is 25% weaker. The Spell Damage table assumes you take half damage on a successful save, but advises increasing the damage by 25% if targets take no damage from a save.
DMG pg. 283
Spell Damage
For any spell that deals damage, use the Spell Damage table to
determine approximately how much damage is appropriate given the
spell's level. The table assumes the spell deals half damage on a
successful saving throw or a missed attack. If your spell doesn't deal
damage on a successful save, you can increase the damage by 25
percent.
Since this spell forces you so that your targets take no damage if your attack roll misses, I compensate by boosting damage up 25%
Closing Remarks and Dilemma
This metamagic changes the way the spell is cast while trying to abide by fair tradeoff rules according to the DMG. This probably gives it a minimum cost of at least 1 SP (and not a higher minimum) because the trade off is fair.
However, it does have a significant benefit. It replaces save DCs with spell attack rolls. This lets you use things like Advantage and Inspiration on your roll to boost your attack. It is not necessarily a strong effect, but with the right party/preparation, I think it can be.
My dilemma is, I can't decide the appropriate total SP cost. I can't seem to find a spell that provides similar advantages to form a basis.
Remembering that 1 spell slot = 1 SP, how many SP should this metamagic cost?
Best Answer
How many Sorcery Points should this cost? Lots. At least 5, since this metamagic is better than Careful Spell, Empowered Spell and Heightened Spell combined. I'm sure you can see where I'm going with this - it's too powerful to put a realistic cost on it.
Your new metamagic option does 3 things. The first is pretty simple - it multiples damage by 1.25, or 1.5 if it's an AoE spell. I'm going to look at Fireball (a pretty classic damage spell) as a standard example.
A Fireball does 8d6 damage, averaging 28 damage. An Empowered Fireball, assuming a Charisma of 20, does 8d6 with the option to reroll up to 5 dice, for an average of 31.75 damage. A Sharpened Fireball does 8d6 * 1.5 damage, for an average of 42 damage.
At this point, you might be thinking "But Fireball does 8d6 damage, where the entry in the Spell Damage table for a 3rd-level spell is only 6d6!" Unfortunately, the advice in the Spell Damage table bears little or no resemblance to the spells that were actually published.
Note that this is also the case for single-target spells. Disintegrate (which uses a saving throw, not an attack roll) deals 10d6 + 40 (average 75), Empowered Disintegrate deals 10d6 with up to 5 rerolls + 40 (average 78.75), and Sharpened Disintegrate deals (10d6 + 40) * 1.25 (average 93.75).
At any rate, hopefully you can see how Sharpened Spell is considerably more powerful than Empowered Spell.
Moving on, the second thing Sharpened Spell does is change the target making a saving throw into the caster making an attack roll. Ostensibly, this is a loss in damage, since most (though not all) spells that use saving throws deal half damage on a successful save. However, it is far easier to make an attack roll hit than it is to make an enemy fail their saving throw.
Firstly, it's a trivial matter to give yourself advantage on an attack roll; it's an extremely non-trivial matter to give an enemy disadvantage on a saving throw. For example, you have inspiration, True Strike, the Help action, the Hide action, The Wild Magic Sorcerer's Tides of Chaos, and heaps of other things to give yourself advantage on a roll. To give disadvantage, you have Heightened Spell, or Contagion. There's not many, and they require significantly more expensive resources than the advantage options.
Secondly, most powerful monsters (the kind that would be worth sharpening a spell for) have Legendary Resistance, which makes it impossible to make them fail their saving throws, since they can just say they didn't. You can make them burn through their uses of this feature, but if they're smart they'll only use it on your best spells.
Finally, attacks are (by design) easier to hit. Everyone uses attacks, and some characters use them exclusively, so monsters can't be impossible to hit without making some players feel useless. On the other hand, not everyone uses saving throws, and everyone can still function without them. It's difficult to prove this mathematically, but anyone can quickly observe that there are extremely few monsters with AC above 20.
A mid-level sorcerer (let's say level 8) with maxed Charisma only needs to roll 12 or higher to hit an AC of 20. With advantage, which you'd better believe they'll find a way to get on their Sharpened Fireball, that's a 69.75% chance to hit.
The same sorcerer casting a regular Fireball has a save DC of 16. Let's assume the monster isn't great at Dexterity saving throws (but not too bad at them, either) and give it a +3. It has a 60% chance of failing that saving throw, which is pretty good odds for the sorcerer, but not as good as the attack roll. On the other hand, if the monster gets advantage on the saving throw (which there are a lot of ways for it to do), it has a 36% chance of failing. Not so good. And, of course, this is assuming a monster with really good AC, which is more of a worst-case scenario than a usual one.
So that's why Sharpen Spell is also better than Heighten Spell. The third thing Sharpen does is change the spell from an AoE to a single-target. This looks like a drawback, and often will be, but in those situations the sorcerer just won't do it. For the sorcerer to be thinking about Sharpening a spell, they'll have a priority target in mind. This lets them use Fireball on the Big Bad without having to worry about hurting their allies. "But they could just use a single-target spell!" Well, they could. But they have a limited number of spells known, and there are in fact no 3rd-level single-target spells. Hence, this is also better (or at least as good as) Careful Spell, albeit only when you have a priority target.
With all that out of the way, this is a really cool idea. It gives us back the Spellwarp Sniper from 3.5, which was great. Focusing Fireballs into concentrated beams of destruction? Awesome.
I strongly recommend going ahead with this, but removing the damage bonuses. If your players choose to use this, they know they're turning an AoE spell into a single-target spell, and they know they're adding a chance of total failure. They'll use it when those aren't problems, so you don't need to boost it because of those drawbacks.
With that change in place, I'd recommend this metamagic option costing 3 sorcery points, the same as Heightened Spell. Wait, what? I said earlier that it was better than Heightened Spell! Well, it is, but it requires the player spending additional resources to make it that way. It's trivial to give yourself advantage on an attack roll, but it's not free. You have to spend an inspiration point, or use your previous turn to cast True Strike or to Hide, etc.