I have a forum-based Pathfinder campaign where one of the players would like to light grease created by a Grease spell on fire. Can this type of grease be lit?
[RPG] Can you light magically created grease on fire
pathfinder-1espells
Related Solutions
Yes, as that's what the rule says you can do. If you are having trouble visualizing it, "steam" might help.
You can freely have e.g. flaming and frost enchantments on the same sword - there's no "they cancel each other out" rules anywhere. If you allow it, you figure out how to justify/skin it, but combinations of "opposed" energies are completely rules-legit.
Note also that you're slightly confusing classically opposed elements like fire/water and earth/air with the D&D energies - acid, cold, fire, etc. Fire is both an element and an energy type, while water is only a descriptor and cold is a damage type and a descriptor. Water is in the spell descriptors but not the damage type; it's a spell with fire and water descriptors but a damage type of fire.
It depends on where they are standing
The darkness spell is described in such a way as to give the impression that it is something tangible that spills out around corners, but can be blocked by objects. Think of darkness as not unlike a fog cloud spell.
The darkness spreads around corners. [...] Completely covering the source of the darkness with an opaque object, such as a bowl or a helm, blocks the darkness.
Likewise, darkness engulfs non-magical light - or rather, it cannot be illuminated by non-magical light. This means that magical light can illuminate it.
Light in 5e is described as having bounds. Faerie fire indicates that afflicted creatures shed dim light, which only means that area imposes disadvantage on Wisdom (Perception) checks; attacking into dim light behaves as normal.
This is where location comes into play. The bounds of the dim light must penetrate the bounds of the darkness spell in order to be seen. Put another way, there must be no darkness between you and the creature. You need to check the positions and radius of the area of darkness and creatures affected by the faerie fire.
If the radius of the darkness spell's area completely engulfs the radius of the dim light, they cannot be seen by you from any angle. If they are 5 feet or more away from the center of the darkness, they can be seen from the direction the dim light is from the center. This is sort of mathy, but really no more difficult than normal line of sight. Darkness spills out around corners continuously, so just visualize or draw the circles and draw a line to the center of the dim light.
Who do I have advantage against?
Advantage and disadvantage hinge on who can see whom. In general, you have disadvantage on attacks against targets you cannot see, and advantage on attacks against targets who can't see you. However, when neither target can see each other (such as when a target is standing in darkness and you are not), you have neither disadvantage or disadvantage.
From the basic rules on advantage:
If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20. This is true even if multiple circumstances impose disadvantage and only one grants advantage or vice versa.
This means that faerie fire's advantage only has an effect when no disadvantage is imposed. It is important to note that, as explained in the question, faerie fire must be cast at a level greater than 2nd, or darkness will dispel it.
You have advantage against:
- Targets you can see that can't see you. It shouldn't matter the circumstances in which this takes place (Devil's Sight, location, etc); if you can determine who can see whom, this will suffice for advantage.
- Targets affected by faerie fire that you can see
- Targets in any situation in which you have at least 1 source of advantage and no sources of disadvantage
You have disadvantage against:
- Targets not affected by faerie fire that you can't see and that can see you
- Targets in any situation in which you have at least 1 source of disadvantage and no sources of advantage
You have neither advantage nor disadvantage against:
- Targets you can't see that also can't see you
- Targets affected by faerie fire that you can't see
- Targets standing in dim light that you have line of sight to (i.e. you can both see each other)
- Targets in any situation in which you have any number of sources of advantage and disadvantage (at least one of each)
This answer hinges on the fact that the darkness spell is dark in 3 dimensions, much like a 15-foot radius of fog or smoke. I believe this is true because of how the darkness spills around corners and can be blocked by objects.
If the darkness spell only "darkens" objects and ground in its radius, then it makes sense to imply that the faerie fire penetrates through it, making line of sight meaningless. Is it a floating black orb, or is it a radius of darkened objects? Again, I say the former, but I would personally leave this up to the DM.
Best Answer
The rules as written don’t allow for the possibility, the term “grease” covers a variety of substances, some of which don’t burn easily, and then regardless there is every reason to think that magically-created grease is not literally the same substance as any mundane grease and therefore would not share the properties not listed in the grease spell description.
On top of that, there is strong circumstantial evidence: in Mythic Adventures, there is an augmentation of the mythic version of grease that makes it flammable. 3.5 had a similar case, a 2nd-level incendiary slime spell that was “grease, but flammable.” These things wouldn’t exist if grease itself were already flammable.
Moreover, grease is one of the best spells for its level in the game, which makes many DMs leery of opening up yet more features for it. On the other hand, DMs also like to reward creativity, so some do allow grease to be lit on fire. You will have to ask your DM for a more solid answer than “the rules don’t say you can, so you can’t.” Or, if you're the DM, you should follow the line of reasoning you prefer to its conclusion.
My first character ever, a sorcerer, had grease as something of a signature spell, and this was one of the first “tricks” I tried with it. The DM didn’t allow it, and considering how much use I got out of the spell despite lacking that option, I think he made the right call, and I’ve made the same call in all of my games since. I have never seen anyone complain that grease is unusable without that feature. Again, it’s one of the best spells out there.