You don't need strength for Necro or Summoning. Don't need Int that much, so pup into wits to go first.
Put more points into Summoning, bc the more points you have in summoning, the stronger your summon gets. If you want, you can even spec into Geo or Hydro for a bit of support with that, but don't spread yourself too thin.
I haven't played with this build much yet, I plan on doing a full summoning playthrough later down the line when im playing solo, so for now I just have ideas bouncing in my head.
As for Necro and warfare, it could definitely work. You can go with 1h+shield, and the necro lifesteal will just boost your Survivability.
Also if you don't like one of your builds and you don't wanna restart, you can Respec after Act 1 for free. That's all I can say without spoilers in terms of that.
