I think Oppressive Gloom would help out more than a power like Soul Tentacles. Stuns provide better mitigation than immobilize for a melee character. DA has the strongest self heal in the game, don't worry too much about the lower hp or the damage OG does. The couple builds I looked at, you have no ToHit or Acc bonuses. You will probably do ok fighting even level enemies but +3/+4 you may miss quite often.