Max hit 208 on a 2291ac tank. Double attacked but didn't notice quads. No ramp, no flurry, no enrage. "Hard hits" - interrupted casting a lot but didn't actually stun.
Seemed very susceptible to magic-based spells (debuffs & nukes).
Dropped shard for Rogue first try.
First instance of this guy in the zone was about 15 mobs in (kobalds > terrors > imps > these). Some stuff sees invis, I think it was the goo.