I did son and I walk you through it.
I had 2 times Scales of Trauma (100% of healing done by Shadow Mend empowers your next Mind Blast Stored damage cannot exceed 200% of your maximum health.), 2 times Catharstick (20% of all damage that you take is stored in the Catharstick. The initial damage of your next Shadow Word: Pain deals this stored damage to your target.) and 4 times Cruelty Censer (You deal 35% more damage to creatures that are feared, horrified, stunned, or dazed.) and 60 more powers.
Scales and Catharstick increase with my HP, and I had 110K plus, so I went into shadow form feared the boss and mind blasted, feared again and used shadow word pain. Boom 90% gone.
You should choose the powers better, some look weak but they are not.