Although, a Shadowknight could in theory kite a mob indefinately, with their pet attacking the mob from behind. Similar to this video I made of killing an Ice Burrower
https://m.youtube.com/watch?v=5fsvt1xfuqY , a Shadowknight could keep agro by chain casting
https://wiki.project1999.com/Blood_Ember_Gauntlets , and keeping distance with JBoots or SoW pots. That means a Shadowknight can kill magic immune targets with enough time and kiting space. Would take forever, but it would be doable.
EDIT: Duh, they could just use disease cloud as well to keep agro. The spell cost is 5, so it is basically free if you have Flowing Thought I and II. Wouldn't be doable on summoning mobs sadly.