As a summoner I aim for:
Warfare 1
Scoundrel 1
pyro 1
Necro 2
Geo 3
All remaining points on summoning and hydro
I need 10 summoning for the champion, 2 necro for the bone widow, 3 geo for artillery plant, 1 scoundrel for adrenaline, 1 warfare for enrage. All are mandatory for my summoner.
I use my AP to summon bonewidow and /w adrenaline give it rage + haste + supercharge for it to destroy something. Maybe delaying it 1 turn. Then I use the incarnate with infusions. I then cycle in artillery plant and repeat. My summoner focuses on a "cycling minions" style of play /w heals, shielding and buffs for the party and summons. I don't actually do any damage myself.