The Difficulty Has Not Increased In Casual Content.

[TaleraRistain]

The Mist Dragon is the only boss I know of in the game that is certain guaranteed death, or all but if the healer gets hit with the AoE.

It does 60% or more of a healer's health in damage at ~350-355 iLevel, and it stuns them for 5-6 seconds, and it puts a DoT that does ~15% health per tick. 3 ticks is death if they did not have a HoT on them at the time.

I don't know of any other MSQ boss that can do anywhere near that much damage in that short of time. No RDM/SMN/PLD = you're done if the healer gets hit with it.

Also, it spams group-wide AoE in fairly quick succession. Rime Wreath is unavoidable and oftentimes right after other AoEs, such as the ice breath (which also puts that ludicrously OP DoT on anybody it hits), the star AoE can oftentimes overlaps and only has a 1.5-ish tell that doesn't give you enough time to get out of it if two of them overlap (which happens rather often). It, too, does the whole cheap Stun+DoT.

No other MSQ boss comes close to this difficulty.

Can't quite agree with you there. Middy in Keeper of the Lake was rage-inducing when he was new content. As well as the entirety of the Vault. Those were both MSQ dungeons that put healers through hell.