i encountered one at level 29 (being a rogue) and was attacked, so, without backstab -the main attack for a rogue- i soloed him without twinkage and bs with half life to spare... it's sad really...
Aye...this bugger healed himself 3 times to almost full health when we fought him. Gets his heals off fast so i suggest either 1) Stun/Mezz him, or 2) Fear him and reverse kite him when you get him at 1/4HP.
Careful not to fear him too soon as they tend to be close to similar level'd friends!