Support build for pve?

I have played ER to death but my friend is doing their first playthrough using seemless coop and instead of me facerolling bosses with a good build or handicapping myself with a bad build i want to make a support build with buffs and such to instead help my friend to beat it mostly by himself

What spells, incantations, weapons or items should i use? the commanders standard seems obvious but other than that ive got no idea