I use Evard's but am not currently spec'ing for conjuration, but i have alot of universal dcs and a decent enough charisma to get good use out of it. It holds a high percentage of enemies in Slave Lords as very few have a spell pen check.
I don't use BoGW on my warlock - I take Ruin/Greater Ruin instead. I was just offering that up as option on his build since doesn't want to take ruin/greater ruin.
Only the cc portion of BoGW has a save. The damage does not have a save as far as I know.