Specifically with shorter characters (like my dwarf I think)
This has happened quite a few times in the last few weeks and I've noticed the common denominator is me being in the group, people are surprised and not very happy. I've noticed when my dwarf gets aggro from epics especially (and other taller mobs, tree ents) he tends to get stepped on and pushed under the earth, so I'm thinking it's him. This triggers the escape/heal which is very annoying especially when fighting the greater epics.
This has NOT happened with Valkor, I think because it's a nice smooth surface. So I either need my dwarf to get a pair of stilts or smooth surfaces where we fight epics. This is really common with Shaloth the queen, but has also happened with diminished surth, sog, AoP, px (not often, but he can get pushed into the things coming out of the ground and sometimes falls into those) and anywhere the surface isn't perfectly smooth.