Originally posted by Gunther Ultrabolt Novacrunch:

I recently tested the troll's aoe (with club) against a pig that i aggro'd into the black forest. Despite numerous ground attacks (with his club) the pig sustained no damage despite being right there in the mix (neither did any of the greydwarfs and greylings).

By indirect damage I was thinking falling tree's perhaps. Here you can see the troll has already broken up a tree (logs) and hit the ground (stones) yet the boar is unaffected:

https://steamcommunity.com/sharedfiles/filedetails/?id=2774199943

Boars and trolls are of the same faction, which is forest.
So i take it trolls dont do dmg to friendlies.

Edit; I dont think there is any team dmg in general, come to think of it.