From the way I read the spell description I am actually inclined to believe that Faerie Fire could be used in the manner that Zinna is suggesting because the spell outlines any objects and creatures within a twenty foot cube; it doesn't say that the creature or object has to be seen by the caster in order to outline them with light only that someone attacking the creature must be able to see it to gain the benefit of it. While the elves are using the foliage of the trees as concealment Faerie Fire would likely outline them in such a way that the leaves and such would no longer be able to break up their silhouette sufficiently. This doesn't apply for any elves hiding behind more solid things like tree trunks though.
On the other hand it depends on whether the trees/leaves are considered objects and whether the spell allows the caster to assign different colors to different objects. The spell description does not say other than stating the it is the caster's choice what color the outline is; but it doesn't say that the caster can assign each object a different color.
I think I will adjudicate it like this: The caster can assign one color to objects and another color to creatures and in this case trees are considered more of an object even though they are living things, unless they are treants, they are not creatures per se.
That being the case Zinna could cast Faerie fire which may outline at least one of the elves and counter the disadvantage currently in place.
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My understanding, which could easily be wrong mind you, is it is also a concentration spell, so it could be lost if Zinna gets hurt. And for it to be effective they have to fail the Dexterity roll, so I think that is fair. And to save us from asking if we have Advantage or Disadvantage on any enemy in particular, may I suggest we all roll twice. If it is normal, Aeric will ignore the second roll. If it is Ad/Disad, he will already have the roll there.
Aeric, since I can use that spell like that can I change my action from Dissonant Whispers to Faerie Fire? If so I will outline the objects as green and the elves as blue. I will keep my bonus action the same. I would target it towards the sound of Adsila's voice. If not possible, I'll just keep the previously posted action.
I assume we are still going in Initiative order. If the group is able to follow Lorilys, Corren will do it, though it dependson whether the elves are visible on his turn. If he can see any, especially Adsila, he most likely will attack.
Quick question about Parsnip's location, is the tree his body is pinned to near enough to Carrick that he could feasibly retrieve him as the group turns and tries to escape with the fog as cover? If that is what the group decided to do of course.
Did we have a chance to grab our horses and gear or no?
I think the only thing of Leo's he wouldn't have taken into the tunnel was his Maul, and I don't think anyone else had bulky stuff of that type. Still would be good to determine what we have with us.