I recently used the Sharn against my 10th level players and it was our most difficult (although very funny and challenging) fight. I swapped the Second Wind for a Teleport 10 that creates a burst 1 of Spellplague fire (10 damage entering or starting the turn there) in the point of origin, used once per encounter.
I just swapped because it looked very grindly as the way it looks (regeneration 20 with tons of hps), and the basic strategy of my players is to immobilize and gang up the solos. Worked very nicely.