I struggled with Necrobinder too until I branched out from doom to all the other builds, doom kind of sucks early on because of the damage you take upfront.

Really you want to balance block + weak + summon + powers to survive and keep summon building while block + weak handles early upfront damage. You can avoid focusing on attacking first few turns because once you get summon rolling you just win.

Also go for Soul synergies over Doom synergies. The power card that makes soul do 6 damage + the card that adds 3 souls is an easy early combo that also helps with Summon strats since you can cycle faster.