My record in beating sinjid's shadow is 5k hp
If only disruption didn't miss so often :(
CHOOSE ASSASIN, KIDS, IF YOU WANT TO BEAT FINAL BOSS!!!
Other classes' speed is low, so the risk to miss disruption(ergo to lose battle) is inexcusably high.
My strategy on Sinjid's shadow:
1) Class: Destroyer(now I regret about the choise)
2) Build: heroic motivationX3, disruption, blood focus, shatter boltX2, break
3) Equip: Assasination(lvl10 prime arms for assasin), Striker's Flip Flops(lvl.8 footwear from shop in area3), and all other equip is from paladin's set. The purpose is to collect as many speed as destroyer posssibly can.
4) Team: Destroyer and Assasin in their sets
5) Tactics: sinjid's shadow shoots manabomb when its mana is full, so all what you need to do is to use disruption when it replenishes its manapool. If you miss(it happens often), you have to restart the fight. Also heal allies and control boss with shatter bolt and break. Also sometimes boss can oneshot you with critical hit. Because of this and disruption's misses defeating this boss is a matter of luck.
P.S.
Did I mention it's a great game?