I think I'd go with Soul Reap still because it's only going to be an issue when it procs and even then I think there's a lot of scenarios in which you can mitigate that. 

That said, you're definitely looking looking for one of the blessings that boosts attack and crit damage.

Lightning Cage is also a strong one to consider. Don't underestimate the value of protecting the buffs on your nuker. Depends a lot on what kind of team you're building around him.