Obviously my elemental resist were capped, I raised my health to 22,931 and my DA to 3,060 (which by the way was not enough to avoid being crit) and my armor absorption to 100%.
The projectiles from that attack would hit me for ~10k damage and yet the attack would often result in a one shot while in melee.
The thing is, it wasn’t consistent: I could tank Mogdrogen for half his life (despite the lowered DA from the Hypporaven) or get one-shot at any time (even at the beginning of the fight without the debuff to DA from the Hypporaven: Shadow Strike Mogdrogen, instant death).
His hit chance were around 80% according the tooltip from my DA. If all five projectile could connect in melee range, I may have survived once or twice out of sheer luck but no more.
My guess is that the projectile splits shortly after its creation. If that’s the case, Mogdrogen move a lot during the fight, there’s a (not-so) sweet spot where a character is in melee range (and thus don’t move closer to the boss) and yet can be hit by all five projectile.
And as I learned painfully Mogdrogen can combo charge, human transformation and projectile burst for an instant unavoidable death.