I am running with pyro/summon/necro on my main, though he is human. The skills work well together.
Rest of the party is a rogue/poly a 2h knight/necro/geo and an support dps as aero/hydro.
I found pyro to be more fitting for my needs, because it also lets me make steam for my hydro to abuse and having haste is just the best thing for sum because you are always lacking ap.
If you goo deep enough into necro you can use the bone spider over your incarnate. It’s not as versatile, but it hits like a truck and also does opportunity attacks. I usually run width both and sacrifice 1 early with empower. That sum spell makes any summon hit 50%harder but it will die at the end of the round. Good fun.
The spider can carry you for quite a while, there is no rush in maxing out sum.
