1) Invulnerable Minions

This trait is absolute bullshit. Cheap as hell, you can't strategize for them, and you have to pray to God that your gear allows you to take enough damage or you have enough energy to kite them. Failing that, it's a corpse run.

2) Fast - Jailer - <insert another random trait here>

Trying to kite this is a f***ing nightmare. As a DH, Caltrops doesn't do shit to them, they can stop you from moving altogether, and if the random trait is Plague/Frozen/Desecrator/Molten, you're going to have to spam Preparation and Smoke Screen to even have a chance to survive.

3) Vortex - Fire Chain - <insert another random trait here>

Fire Chain hurts like a motherf*cker and Vortex usually sucks you in between the bunch of mobs.

4) Arcane - Waller - Plague/Desecrator/Frozen/Molten

This is a nightmare in narrow areas like dungeons. All of them restricts your movements and set up so many death zones that it's not even funny.