So I made my main character a summoner. While I do believe that summoning, just like in the first game, makes it to easy to distract enemies, soak hits and deal damage with no real penalty (and other reasons described by Testing here
http://larian.com/forums/ubbthreads.php?ubb=showflat&Number=618180#Post618180) and is generally the easiest of all the combat skills, it seems to me Larian forgot to balance the scaling of non-summoner creatures like the bone widow, artillery plant and others.
Let's look at the Bone Widow first.
All the following summons are based on a level 13 character with 10 points in summoning.
First of all, I realize that the bone widow costs one AP more than the Incarnate, despite this the Bone Widow has significantly more HP and more damage output.
Even with a power infusion which equalizes the AP cost, the Incarnate will have a combined hitpoints of just roughly 1600 compared to the Bone Widows 3700. Keep in mind that the bone widow also has a teleport ability, which you would additionally have to infuse on the incarnate, driving his cost up to 4 AP. Even then, the Bone Widow will deal 1/3rd more damage and has Double the overall HP.
You could argue that the lack of magic armor makes the Bone Widow very vulnerable to CC, but that is neglectable because of the massive healthpool.
Think about that for a second. 3700 HP at level 13 with 10 points in summoning. With half my attributes in constitution, my player characters have just around 1100-1200. No enemy at an equal level could possibly kill it until the 5 turn cooldown is down, where I can just recast the creature. 300 Damage is more than any of my main characters weapon attacks can deal.
Yes, the Incarnate is more versatile, yes it can potentionally deal every damage type, but if I have to spend more Action Points on it than on the Bone Widow, to have LESS than half HP and deal 2/3rds of the damage, why shouldn't I just start with a widow everytime and spam totems afterwards? What does the damage type matter when the bone widows kills any enemy before the Incarnate regardless?
Now let's look at the Artillery Plant.
This time around it's not the healthpool that is what catches the eye, but the damage. The Bone Widows damage is already higher than anything the Incarnate can dash out, but the Artillery Plant makes both pale in comparison.
Here I compared the Artillery Plants ranged attack (spore attack) to the Incarnates Infused ranged attack.
Both of these summons then take 3 AP to cast, with the addition of a Source Point for the Artillery Plant.
You could dismiss this as the source point justifying more damage, but thats 1081 damage against 182, no crits.
No other skill ( that requires one source point) that a player character can learn can deal this much damage. Most other source based attacks at level 13, with 10 points in the respective skill, deal around 300-400 damage.
It's even more absurd if you consider that a Geomancer can learn the same skill that the Artillery Plant is using, but he needs 2 source points and 3 AP, while the Summoner can cast the Artillery plant for one source point, which then can cast this attack without source, two times before it dissapears after 5 turns, WHILE the summoner is free to do anything he likes afterwards.
Why are the non-summon summons so much stronger overall? The Incarnate is the summoners main pet, he is designed around it, afterall most his skillbooks add on it.
The only explaination I have is that it's simply an oversight.
I think the devs didn't playtest how these skills scale when used by a summoner main instead of a necro/geomancer.
With no points in summoning, the bone widow and artillery plant seem much more reasonable, thats how they were probably designed.
With points in summoning, it just breaks the game.