Strangely, last night we actually KILLED Malgus. Straight up he was dead at my feet.
He initiated the 1v1 against me before he went invul and our dps was god enough that we got him to about 5-6%
when he went 1v1 against me. At that point I was able to drop him the remaining 5% and he just died right there.
Everyone in the group was kind of stunned ...
Yeah, this is kind of interesting. Malgus goes into the last phase of the fight when he crosses the 10% health threshold. But when "Filling X's Head WIth Doubt" comes up it triggers a solo portion of the fight and the invulnerability won't kick in until Doubt is finished. If you have a good group they can burn the last bit of health during this phase and he'll drop dead.
Edit: Incidentally, I prefer finishing FE this way. There have been too many times during the last phase where he's shooting lightning at the group who has run to the faaaaaaaaaar side of the map. It's a little difficult to knock him over the edge if he stays on the stairs and won't move. :/