Durendil: There are two problems on this boss: he hits like a truck, and the proto-behemoth’s fireballs do too much damage for you to survive long. So you’ll need to have the time warden up to stand a chance. However, since you can only free one drake, if he has the attack speed buff or the mortal wounds, your pet doesn’t stand a chance. So bronze/green/nether combo is, for the moment, the only possible combo.
Start the fight by freeing the warden, then use stampede and all CDs. Blow quintuple last stand at the last possible moment, and make sure you kill the drake before it expires. Then the rest of the fight is kiting the boss when your pet is low on health/has no cooldowns ready. He’ll start roaring at 50%, which makes survival easier. Just make sure you aren’t bumped in the lava.