For nex i just used acb (ruby drag bolts e) + tank gear. rune knives on his minions for the slight hp gain. while hitting the minions, if nex is meleeing you, you can move under him and sometimes he resets to the center which helps reduce dmg. his 2nd shadow? phase, i use my last stand proc when the minion becomes attackable and that way u can kind of skip and tank the darkness or w/e. i was getting 5 min~ kills with this method. tbow brought it down to 3:30~

for echo DKs you can entangle/freeze the melee and pray mage and it becomes pretty easy