The Shaitan Binder is an interesting Archetype that seems to be almost totally neglected. I am pretty sure I have never even heard anyone mention it. The link is- http://www.d20pfsrd.com/races/other-races/featured-races/arg-oread/shaitan- binder-summoner-oread.
The archetype alters a bunch of the class features, notably giving the Eidelon all 4 Magic Using evolutions for free. You also get to earthglide and trap enemies in stone and finally the Eidelon can cast Limited Wish at level 20. On the face of it you seem to get far more than you give up.
There are downsides, you have to be an Oread, which is hardly the best race for a summoner with a -2 to Charisma. And using evolutions to gain SLAs does not strike me as the most effective use, but you get them for free.
What do others think?
It loses Share Spells--that's kind of a big deal. It also gets the most benefit from being bipedal, which, because of no Pounce, is strictly inferior to Quadruped.
The free evolutions replace mostly ignorable abilities, but they're also not very useful to begin with. Earthglide and Entrap are ok, but awfully high level.
I don't know, I don't think there's anything especially worth taking unless you just really wanted the flavor.
It's just not very good, sadly. While the evolutions are 'free' in the sense that you don't have to pay evo points, you're still trading out class features to take the archetype in the first place. In particular, you lose share spells (severely limiting the buffs you can grant to your eidolon) in exchange for a +2 to one ability score, but only if you use the biped base form. Either you've lost a huge amount of buffing power for literally nothing, or you're locked to one form forever to keep a bonus that still won't make up for the spells you could've cast.
The free versions of the magic evolutions suffer badly for three reasons. First, the caster level for the gained SLAs is based on eidolon hit dice, which lag behind from 4th level onward. Second, the DCs are based on a combination of lagging hit dice and Charisma, the stat eidolons start with an 11 in and can only raise with 2-point evolutions. Third, all of the magic evolutions are once per day, unless you spend points to buy the upgraded versions. Between the Charisma increases and the 3/d costs, an eidolon trying to make the SLAs usable is going to run dry very quick boosting their 'free' evolutions. And, of course, you lose shield ally in exchange, which was a great buff to the squishy summoner.
Earth Glide is worth having if you took burrow, but you still have to buy burrow to benefit, so that's another 3 points down the drain. Stone Curse comes far too late to be relevant, considering it only works on bull rush builds. You lose aspect for those two abilities, but since you won't have any evolution points left on the eidolon anyway, I guess it's not a big loss.
And finally, Limited Wish 1/d at 20th level. That's nice, I suppose. So the 20th level Shaitan Binder gets his eidolon to grant lesser wishes, and still has to pay the material costs of anything important. Meanwhile, the 20th level summoner in general can cast gate out of their summon monster pool. Gate can call actual genies, who fall under your control because your caster level exceeds their hit dice. Said genies can grant actual wishes at no cost whatsoever, and if they balk or are evil, you can just threaten them with your actually-functional eidolon. Or two of them, because you didn't give up twin eidolon as your capstone.
OK, you have convinced me. Sad but true.
I realised before posting it was not as good as it looked at 1st glance.
You may well be able to come up with something at least acceptable by using the Eidelon atypically, not going into melee that much, along the lines suggested by Dafydd.
On a side note, can this archetype be applied to the Unchained Summoner?