@Goldfish, I sat down and made some stats for Wildfyre, greenlit by DP.
Wildfyre
This green substance will readily ignite when dispersed or coming into contact with flammable materials, producing a bright green flame that is magical in nature and will readily devour both magic and mundane materials to sustain itself.
Wildfyre is usually used as ammo for siege weaponry, since few would dare to throw a flask of it manually. A siege shot of Wildfyre deals 4d8 damage to anything within 5ft. of where it hits and 2d8 damage to everything in a radius of 30ft. around that. A small flask that can be thrown manually is a splash weapon with 10ft. range increment and deals 1d8 of damage to anything it hits. Creatures adjacent to where this flask hits must pass a DC 10 reflex save or also take 1d4 damage. This damage is half fire and half profane damage.
Once hit, any creature or object affected by Wildfyre takes the same damage it initially took each round. Furthermore, at the end of a round, any adjacent square, creature within a square or square where a Wildfyre affected creature stands is also set ablaze, taking damage one damage dice step lower then the source from that round onward. So a square burning with 1d8 of Wildfyre damage will set all adjacent squares on fire for 1d6 of Wildfyre damage at the end of the round and so on. A creature can attempt to extinguish itself by making a DC 15 reflex save. On a success, the damage it takes is reduced by two steps, on a failure it is still reduced by one step. A creature can also attempt to extinguish another creature or object as a full round action, lessening the damage take by two steps, but the creature must pass a DC 15 reflex save to not set itself ablaze. Wildfyre keeps burning even without fuel, lessening only by one damage die step per minute it has no fuel.
Furthermore, Widlfyre resists attempts to magical extinguish it and actively damages enchantments and ongoing magical effects. Each round a creature or object takes damage from Wildfyre, it is subject to an affect equal to a Dispel Magic with a caster level equal to half the damage taken by the Wildfyre. When attempting to magically extinguish Wildfyre, roll the damage for the fire and deduct that number from the caster level of the spell or affect as the Wildfyre consumes the magic it is made up of. If the effect is reduced to a caster level of 0, it fails entirely. When hit by a Dispel effect that overcomes a DC of 15, Wildfyre flames in the affected area become mundane fire for 1d4 rounds and can be extinguished as normal. After that time, it regains its magical properties but looses one damage die step per round it was suppressed.
Wildfyre deals full damage against objects and ignores hardness below 20. Valyrian Steel and Imperial Steel are immune to the effects of Wildfyre.
Cost: 500 GP per flask, 5,000 GP per siege shot, DC 30 Craft Alchemy