Can I use Metamagic transmutation on Chaos Bolt?

Question

Was wondering if it is possible to use metamagic to transmute the damage type of chaos bolt.

Sorcerer Metamagic gives a number of options for modifying spells, Transmuted Spell reads:

When you cast a spell that deals a type of damage from the following list, you can spend 1 sorcery point to change that damage type to one of the other listed types: acid, cold, fire, lightning, poison, thunder.

Technically speaking chaos bolt "deals a type of damage" listed. However, chaos bolt can also deal other damages and may at the time of casting (as it is randomly determined).

Chaos Bolt

You hurl an undulating, warbling mass of chaotic energy at one creature in range. Make a ranged spell attack against the target. On a hit, the target takes 2d8 + 1d6 damage. Choose one of the d8s. The number rolled on that die determines the attack’s damage type, as shown below.

So my question:

1. Does chaos bolt qualify for transmutation?

2. Does chaos bolt always qualify for transmutation even if you roll something not listed? (Its a bit unclear if the spell has to 'be able to deal' the damage or has to actually deal damage in order to be transmuted).

Answer 1

Transmuted spell reads:

When you cast a spell that deals a type of damage from the following list, you can spend 1 sorcery point to change that damage type to one of the other listed types: acid, cold, fire, lightning, poison, thunder.

When you cast a spell, you can choose to spend the points.

However Chaos Bolt says:

On a hit, the target takes 2d8 + 1d6 damage. Choose one of the d8s. The number rolled on that die determines the attack’s damage type, as shown below.

At the time of casting you do not know the damage type of Chaos Bolt, so it is not possible to transmute the damage type as it does not qualify for this metamagic.

As always, ask your DM. They may allow you to come to some compromise.

Spells take effect when they are cast

In the rules for spellcasting they state:

In casting a spell, a character carefully plucks at the invisible strands of raw magic suffusing the world, pins them in place in a particular pattern, sets them vibrating in a specific way, and then releases them to unleash the desired effect--in most cases, all in the span of seconds.

You cast a spell -> the spell takes effect.

The effect of the spell isn't part of the casting, it's the result of the casting.

Answer 2

Chaos bolt qualifies for transmutation after it deals damage.

There are two conditions for the Transmute Spell trigger:

1. You cast a spell.
2. That spell deals a type of damage from the list.

Note that #2 says "deals". Transmute Spell triggers when the damage is dealt. (I'm working with the interpretation of similar language in this Q&A and this more recent similar question, which reads "When you cast a spell that restores hit points", but successfully triggers only after hit points have actually been restored.)

Your combat flow looks like this:

1. Successfully hit something with chaos bolt
2. Roll damage and determine type
3. Spend sorcery points to transmute damage
4. If chaos bolt jumped to other creatures and the new damage type has not already been transmuted, start over from step 1. (One usage of Transmute Spell suffices to transmute all potential damage of the type transmuted.)

Answer 3

Yes, but you won't know what you're getting.

As you quoted, with relevant highlights:

When you cast a spell that deals a type of damage from the following list, you can spend 1 sorcery point to change that damage type to one of the other listed types...

Therefore, when you cast chaos bolt, you can choose one of the damage types on that list and change it to another. Then, once you determine the damage type of chaos bolt, if you roll the chosen damage type, you will instead deal the new (transmuted) damage type.

Since the language used is simply whether or not the spell 'deals a type of damage', and there is no further specification on when, or how much of the time, or anything of the sort, it is enough that the listed damage types are on the roll table. However, as you see, it's not often too useful to transmute this rather chaotic spell!