Hehe, yeah, well, I will be running 2 Doomguards every second of the Dungeon, and sometimes 3 depending on the boss.

Metamorphosis will be on a 2:10 Cool-down, then add in the 30 seconds of the spell. So it would be down to 1:40 Cool-down.
Demonic Empowerment will be down to 42 Seconds. I know it dosen't work on Doomguard, but it will help with speeding up runs.

Right now all bosses are pathetic. With so many dots going on them, they drop really fast. All I Do for them is dot(s), and Drain life. I don't even touch Shadow Bolt. Though, I may throw in a Soul fire or 2 (With Meta up of course).

My pet is sitting at 7.5K (Void) But I think the Doom Guard gets more HP.