Aha!
Somewhere I am useful!
Firstly, define a material called Flame.
For an example on how do define a material, we will look at the Cave Floater raws.
[USE_MATERIAL_TEMPLATE:POD_JUICE:CREATURE_EXTRACT_TEMPLATE]
[STATE_NAME:ALL_SOLID:frozen cave floater juice]
[STATE_ADJ:ALL_SOLID:frozen cave floater juice]
[STATE_NAME:LIQUID:cave floater juice]
[STATE_ADJ:LIQUID:cave floater juice]
[STATE_NAME:GAS:cave floater gas]
[STATE_ADJ:GAS:cave floater gas]
[MELTING_POINT:9950]
[BOILING_POINT:10000]
[PREFIX:NONE]
[SYNDROME]
[SYN_NAME:cave floater sickness]
[SYN_AFFECTED_CLASS:GENERAL_POISON]
[SYN_IMMUNE_CREATURE:CAVE_FLOATER:ALL]
[SYN_INHALED]
[CE_FEVER:SEV:50:PROB:100:RESISTABLE:START:50:PEAK:500:END:1500]
[CE_NAUSEA:SEV:35:PROB:100:RESISTABLE:START:50:PEAK:100:END:300]
[CE_DROWSINESS:SEV:75:PROB:100:RESISTABLE:START:1000:PEAK:2000:END:4000]
[CE_DIZZINESS:SEV:75:PROB:100:RESISTABLE:START:1000:PEAK:2000:END:3000]
Now, we don't want a syndrome on the extract.
We also want it to be a gas at room temperature.
I'm leaving out the IGNITE_TEMP tag, because I'm not sure how that would work with gasses.
Feel free to try it out yourself though.
Here is my idea of a flame:
[USE_MATERIAL_TEMPLATE:DRAGONFLAME:CREATURE_EXTRACT_TEMPLATE]
[STATE_NAME:GAS:flame]
[STATE_ADJ:GAS:flame]
[MELTING_POINT:9950]
[BOILING_POINT:10000]
[FIXED_TEMP:20000]
[PREFIX:NONE]
This makes the fire hotter than magma. From personal experience, the world will burn.
Now, how do we make a creature attack with this?
Personally, I'd attach it to a bite attack.
Looking at the Helmet Snake attack:
[ATTACK:BITE:CHILD_BODYPART_GROUP:BY_CATEGORY:HEAD:BY_CATEGORY:TOOTH]
[ATTACK_SKILL:BITE]
[ATTACK_VERB:bite:bites]
[ATTACK_CONTACT_PERC:100]
[ATTACK_PENETRATION_PERC:100]
[ATTACK_PRIORITY:MAIN]
[ATTACK_FLAG_EDGE]
[ATTACK_FLAG_CANLATCH]
[SPECIALATTACK_INJECT_EXTRACT:LOCAL_CREATURE_MAT:VENOM:LIQUID:100:100]
Now, we keep all of that, except we change the extract to be DRAGONFLAME:GAS
[ATTACK:BITE:CHILD_BODYPART_GROUP:BY_CATEGORY:HEAD:BY_CATEGORY:TOOTH]
[ATTACK_SKILL:BITE]
[ATTACK_VERB:bite:bites]
[ATTACK_CONTACT_PERC:100]
[ATTACK_PENETRATION_PERC:100]
[ATTACK_PRIORITY:MAIN]
[ATTACK_FLAG_EDGE]
[ATTACK_FLAG_CANLATCH]
[SPECIALATTACK_INJECT_EXTRACT:LOCAL_CREATURE_MAT:DRAGONFLAME:GAS:500:500]
[SPECIALATTACK_INJECT_EXTRACT:LOCAL_CREATURE_MAT:DRAGONFLAME:LIQUID:200:200]
I can confirm that this kind of attack works, although I haven't tested these exact materials.
Well, it worked when I made my dwarves release bursts of slade on a scratch.
The slade would superheat the enemy, and the liquid slade would boil the area that was attacked, as liquid sprayed over the area, continually heating the limb.
Also, the attack didn't release the slade every time. Attacking unarmoured areas, or the feet, seemed to do it the most.
When a cloud of dragonfire is released, it generally spread 2-3 spaces away, doing some heat damage to anything within 2-3 spaces.
Someone else will have to help you with the colourations.
The reason this works is that the material does not enter the blood, as it does not have the tag to do it. Instead, it simply sprays on the outside, as a real material.