The new Metamagic option, Transmuted Spell, allows a spellcaster to change the elemental damage type of one spell they cast for another elemental damage type. For example, a spellcaster could cast the Fire Bolt spell and then use Metamagic to change its damage type from fire to cold (effectively creating an Ice Bolt, if you will). This transmuted spell works just fine if you target a creature with this spell, since it would just take damage as it normal would from the spell. But what would happen if you target a flammable object with this Ice Bolt? Would the spell set the target ablaze as it normal would? Or would the target fail to ignite?

My gut opinion is that the spell would need to deal fire damage in order to ignite a flammable object, as that's just common sense. But when I look at the Transmuted Spell from a literal perspective, there is nothing to suggest that anything besides the damage type is changed when you transmute the spell.

Common sense aside, the spell's effect ignites objects. The metamagic does not change that. So that is what the RAW says happens.

It is up to DMs to decide if this makes sense or not and overrule it.

It does not make sense, but RAW, Fireball ignites objects no matter what damage type it dealt.

Obviously, as a GM, I can handwave it if my players wishes me too, but if they want me to stick with RAW, then I am going to have the spell ignite things. If my players want to take advantage of the fact that subjecting an object to rapid temperature changes would cause it to weaken or shatter, due to cold damage and then being ignited, I would allow that too.

I would say that a transmuted spell still has all other effects. So a fire spell changed to be cold, acid, lightning, etc still lights stuff on fire. It doesnt have to make sense. A ball of cold wind which subsequently lights stuff on fire sounds pretty darn magical to me. 

As a wise man once said: "It's magic, I dont have to explain sh*t" 

This discussion is also interesting when considering the Order of the Scribes wizard. The interaction between magic damage and other spell effects can be odd, but flavorful. One place where I feel the interaction is super relevant is the spell Vampiric Touch. 

The spell effect explicitly states that you heal for half of the necrotic damage that the spell deals. So what happens if use my awakened spellbook to change the damage type of vampiric touch to psychic damage instead? 

I would feel inclined to say that you don't heal, as the spell effect (which shouldnt change per RAW) explicitly relates the healing to necrotic damage, but I could see DMs giving it a pass. 

It's a shame there are only 4 poll options. I don't think any are correct.

Not every spell which does fire damage ignites objects. Some, like scorching ray and wall of firemake no mention of igniting objects. Others, like burning hands and fireball explicitly mention ignition.

The spell only does what it says it does. Changing the damage type doesn't change ignition; as weird as that sounds. This means even if you transmute the damage of a spell that causes ignition to something other than fire, you still set objects on fire.

Quote from Kaboom979 >>

This discussion is also interesting when considering the Order of the Scribes wizard. The interaction between magic damage and other spell effects can be odd, but flavorful. One place where I feel the interaction is super relevant is the spell Vampiric Touch. 

The spell effect explicitly states that you heal for half of the necrotic damage that the spell deals. So what happens if use my awakened spellbook to change the damage type of vampiric touch to psychic damage instead? 

I would feel inclined to say that you don't heal, as the spell effect (which shouldnt change per RAW) explicitly relates the healing to necrotic damage, but I could see DMs giving it a pass. 

 I would say that if you change "necrotic damage" to psychic damage with a feature, then "regain hit points equal to half the amount of necrotic damage dealt" becomes "regain hit points equal to half the amount of psychic damage dealt."

That doesn't quite do beyond what the RAW effects says.

I think it would work, but it's also worth remembering that vampiric touch isn't on the sorcerer's spell list.

Quote from Jounichi1983 >>

I think it would work, but it's also worth remembering that vampiric touch isn't on the sorcerer's spell list.

 The reason I brought this example up was because Vampiric Touch is on the wizard spell list, and the Awakened Spellbook feature of the Order of the Scribes subclass for wizards has a similar effect to the transmute spell metamagic  

You could also make this argument from the opposite angle - what about extra effects the spell should cause. For example the fireball spell describes  it as 'blossoms with a low roar into an explosion of flame'. Surely if you replaced this with thunder damage it should explode with a massive boom?

RAW, if the only thing changed is the damage, then the spell would still "ignite" the object.  A question that I have is do the rules address what that means?  As far as I can tell there is no guidance for what an ignited object takes in terms of damage or if a creature takes damage if they tried to grab said object, or what a creature might have to do to stop the burning (use an action?).  I know there are specific monster effects and item effects that go into this detail, but none of the spell ones do.

Without that guidance, the DM could just describe an alternate effect for "ignition" such as creeping frost spreading over the object (cold), advancing decay (necrotic), amplifying vibrations (thunder), corrosion (acid), etc, assign damage over time, and then adjudicate a way for the players to stop the damage from proceeding turn to turn.  Some forms of damage, like radiant and lighting, could still ignite the object in the traditional sense, btw.

Quote from iconarising >>

RAW, if the only thing changed is the damage, then the spell would still "ignite" the object.  A question that I have is do the rules address what that means?

Not even a little bit.  If you ignite e.g. rope, there's not even guidance on how much fire damage to inflict on it each round (including 0, if igniting isn't intended to cause fire damage each round).  The DM has to rule on it without any idea of what's appropriate.  There is guidance on how much fire damage an object can take before it's compromised.

Page 4 of the DM Guide says to abandon the rules whenever you see fit. This is not a game where every conceivable combination of abilities is even considered, and nor should it be.

Use basic common sense.

If you change the damage to cold instead of fire, of course it doesn't set things on fire.

Quote from Sanvael >>

Page 4 of the DM Guide says to abandon the rules whenever you see fit. This is not a game where every conceivable combination of abilities is even considered, and nor should it be.

Use basic common sense.

If you change the damage to cold instead of fire, of course it doesn't set things on fire.

 Or it does, because magic doesnt have to conform to classic views of common sense. Its magic. Snow that sets stuff on fire is perfectly magical 

This is the most forum thread ever. What does the word "flammable" even mean? Who cares?

If y'all want magic snow that sets stuff on fire, then cool, have that. It's still doing fire damage.

Quote from AntonSirius >>

This is the most forum thread ever. What does the word "flammable" even mean? Who cares?

If y'all want magic snow that sets stuff on fire, then cool, have that. It's still doing fire damage.

 That last sentence is actually untrue, as the entire point of the thread was focused around features (specifically the transmuted spell metamagic option) which changes the damage the spell deals. 

The more specific example is a Fireball which now deals cold damage also igniting flammable objects that has people in a tizzy 

I would rule that it ruins objects in a different way depending on the damage type it was transmuted to.

I.E. The cloth is burned by the lightning, the cloth is petrified by the cold, the thunder tears the cloth.

Not sure how poison would work, though.

Quote from Kaboom979 >>

Quote from AntonSirius >>

This is the most forum thread ever. What does the word "flammable" even mean? Who cares?

If y'all want magic snow that sets stuff on fire, then cool, have that. It's still doing fire damage.

 That last sentence is actually untrue, as the entire point of the thread was focused around features (specifically the transmuted spell metamagic option) which changes the damage the spell deals. 

The more specific example is a Fireball which now deals cold damage also igniting flammable objects that has people in a tizzy 

You have it exactly backwards. If you want it to set things on fire, it has to do fire damage. 'Flammable' has an actual definition, and it isn't "easily catches fire when it gets really cold". fireball ignites flammable objects.

A bright streak flashes from your pointing finger to a point you choose within range and then blossoms with a low roar into an explosion of flame. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one.

The fire spreads around corners. It ignites flammable objects in the area that aren't being worn or carried.

Those highlighted words are not independent of each other. They all refer to the same process. If you change 'fire' to 'cold' throughout the spell, it affects words like 'ignite' and 'flammable' too, because those words have fire as part of their meaning. (That would, therefore, mean the DM would have some latitude in creating different secondary effects from your transmuted fireball. Standing water would freeze in a coldball. Objects might melt rather than ignite in an acidball. Etc. etc.)

If you transmute a fireball into doing cold damage, it would no longer set things on fire, because flammable objects don't catch fire in the cold. No fire, no... well, fire.

What you want for your magical burning snow is to cast fireball normally, but due to your specific character's bells and whistles decide to flavor it to look like a big snowball. Then you can have your snow that sets things on fire. Because it's still doing fire damage.

Contrast that with ray of frost, which implies that it's reducing a creature's speed because it freezes them but doesn't actually say it outright:

A frigid beam of blue-white light streaks toward a creature within range. Make a ranged spell attack against the target. On a hit, it takes 1d8 cold damage, and its speed is reduced by 10 feet until the start of your next turn.

If you transmute that one into fire damage, the target's speed would still be reduced, because the secondary effect isn't intrinsically tied to it being really cold.