So is anyone else noting how goddamn annoying this is? Mainly because Keleseth LOVES running up and one shotting you for 70,000. Also the dark nucleii seem to love aggro-ing onto melee when they run through them.
I made a video of my experience for anyone else doing this http://www.youtube.com/watch?v=4Rt35WpmYmw (still processing), hopefully this is fixed soon.