The reason I specifically ruled out Apotheosis is because it is way too strong. As I explained in the tips & tricks thread, it's entirely possible to do 30.000 damage to every enemy in the fight within the first two rounds, with a single character, using that skill. So if there are 5 enemies, that's 150.000 damage in two rounds.
It's broken beyond belief, especially when used by Lone Wolf characters, as they can max out way more skills, get way more high end source abilities, and offload all of them in a few rounds due to the extra AP.
Definitely, it's a strong skill - but with those numbers you're talking the very end-game where it's supposed to be a little ridiculous.
You can get it a level 16 - where the numbers are very different.
But if you don't want to use the best skills in the game, I can certainly understand why you think summons are THAT good.
The reason you're dealing that much damage at the end is because of the way scaling works in the game, which is why I said dedicated damage dealers are superior to summons.
Apotheosis in itself IS pretty sick with the +4 stats - but the big numbers are derived from the other skills in themselves.
But, true, source skills are much more powerful than normal skills - and they should be.
The bottom line is that "of the rest", both incarnate and bone widow yields the most bang for your bucks. Those 3 AP will do way, way more overall damage than the likes of Flurry (Scoundrel), All In (Warfare), Infect (Necro), Flay Skin (Poly), Ice Fan (Hydro), Dazing Bolt (Aero) and so on and so forth.
I have no problems with it either, given the required investment, but it is the most efficient 3 AP you can spend outside of certain source spells/abilities, which means it can be a massive, almost "free" boost in power to most specialist characters, such as 2x huntsman (tactical retreat), 8x warfare and 10x summoning. It's almost mandatory for Lone Wolf characters, as it only requires 5 points there, and can provide both tanking and a good bit of damage for just 3 AP / 5x rounds.
First of all, you forget that you invest 10 points in summoning to max it out - which is 50% damage you're missing out on if you put those points somewhere else.
For a Rogue, for instance, every single point I put into my skills will directly contribute to damage for everything I do. Meaning I can add 50% to everything compared to a character that has maxed out summoning on top of his other skills.
Also, summons have WAY less mobility than a normal character has - including at least three 1 AP teleports (with one of them actually being a strong attack in itself), which means you're going to waste a ton of AP going from enemy to enemy if you want your summon to work on more than one of them.
I keep watching my brother waste his turns having to actually move to the enemy - which means 0% damage during that time.
Yes, summons are strong - and they should be, because you should be rewarded for going all out on something that won't directly contribute to output.
If you want to powergame, you can't stare yourself blind on individual skills and just do the numbers - you have to take everything into consideration including things that aren't straight-up damage boosters.