Now for a similar build, but without the slam cheese.

Now 26 evolution points. Yeah, your half-elf will have little room for any other feat. But, face it, if you are a half-elf Wild Caller, you do play second fiddle to your eidolon. Just buff 'im, and stay out of his way.

Still huge. That extra strength (16), extra damage and so on is too good to pass on. 10 points.
Still pounce. You need to be able to use all attacks, or this build is down the drain. 1 point.
Lotsa arms. As many as you can get, which is at this point 14. 14 points.
1 point left. Pincers would be a nice addition. This also means that you get 3 natural attacks, which is nice, because you now can fully use the multiattack feat your eidolon gets for free.

Still the same feats, except you you don't need improved natural attack, and we will use Aklys as the light weapon of choice. Partly because they do more damage (medium size damage is 1d8) and partly because they are silly.
Also, the main hand will be a bastard sword (or dwarven waraxe, same average damage).

So, damage.
Still enlarged, but we will use Mighty Strength instead of Strong Jaw. Same spell level, though a cleric spell instead of a druid spell. It also has the same duration. It is an enhancement bonus, so when our half-elf finally gets his act together, and buys his eidolon a nice belt O' strength, it wont stack.

Anyhoo, that gives us a to hit of +20, and a damage bonus of the aklys of +14 (+7 for the natural attacks).

Bite is now 2d8 +7
Pincers are also 2d8 +7
Aklys are 4d6 (I think?) +14
Bastard sword is 4d8 (I think?) +14
Damage is 11.76 (1 bite) + 23.52 (2 pincers) + 267.54 (13 aklys) + 23.68 or 326.5.
With the DR, it is reduced to 265. A note on the DR, the dragon's DR is only 5/magic, so all attacks that hits, actually damage the dragon. But higher DR might stop some of the attacks completely.
Yeah, there is an iterative attack, but I couldn't be bothered. The extra damage would be around 16, or 13.5 with the DR.

Now this seems like a higher number than with the slam attack, and it is , but it is misleading. You would also use some sort of strength enhancer on the other build. Without the extra strength, the damage is "only" 195 (ish). I suspect that what really hurts, is the lower to hit, and not the less damage.
It is also quite expensive to equip your eidolon with 14 decent weapons. It would cost 28000 gp just to get +1 weapons, and it would be needed to get through the DR/magic that just gets more frequent and higher. If only the spell Greater Magic Weapon worked as the natural attack version did. It also lacks any ability to get through any other DR.

What this does illustrate, I think, is that the Kali build is a potential insane damage build. It can, if it has a rich uncle that died, leaving it his collection of antique collectors magic aklys, kill two young adult red dragons each round! Of course, you would probably have to take a set of arms away to give it flying, but this is TO, not reality.
The Kali build rules damage output for the first 5 levels or so, until DR becomes something that every BBEG and his neighbour has.

An actual illustration though, of a quadruped with pincers on its feet, having 14 arms, wielding small hooked throwing clubs in all of them but, with all clubs tied to the quadruped with a 20ft. cord, and a claymore in the last hand, yeah, no...

This build, as its arms increases in numbers, should slowly transform its name towards hundredhanded.