I finally figured out my favorite Warlock summoning build for soloing offline in an 8 player game.
The five skills I'm maxing: Demonic Mastery, Goatman, Bind Demon, Death Mark and Sigil Lethargy.
If I make it all the way to Level 99 then I'll dump my remaining points into Blood Oath. 1 point wonder otherwise.
Sigil Lethargy is just so effective. It can break Hell physical immunes and it stacks with Decrepify and Holy Freeze.
I'm slowing everything down for crowd control and safety. Also works well against bosses and champions. Overpowered in my opinion.
But anyway. Lately I've been playing my Blizzard Sorc to rune farm and going to find some items for my Summon Warlock to use first.