Is it intended that Mark of Ursol doesn't count as Active Mitigation for Molten Crash? As a nature based ability, the natural AM choice to make would seem to be mark, but then you get the knockback and extra damage effects. To stop those, you have to use Ironfur, even though its armour and doesn't help against the attack's damage.
To me, this seems wrong. Monks, Paladins and Warriors can all use AM that works on this attack. Perhaps the others too, although I am in no position to check that at the moment.