In my opinion, you are approaching the idea of the Incarnate incorrectly. Before initiating a combat, check the opposition to see what they are most vulnerable to. Summon an incarnate based on that. To be more specific, if creatures in an encounter are resistant or immune to fire damage, putting points into Pyro in an attempt to buff an Incarnate summoned from fire will be useless. In such a case, it is likely the creatures will have water vulnerability and summoning a water Incarnate will be best.
Given this, after maxing out Summoning, either select skills that will allow your character to deal damage or pump up leadership to buff the Incarnates resistances. If you are at a loss, put a couple points into Aero as Teleport is arguably the best utility spell in the game both in and out of combat. Put a point into Pyro to pick up Peace of Mind and Haste to buff the Incarnate. Put a couple points into Warfare to Enrage the Incarnate.
