This is a character concept that I am looking at.
Gathlain stats look like-
Str 8
Dex 16
Con 12
Int 12
Wis 10
Cha 18
A Broodmaster starts with 2 small eidelons. Mine will be one that is combat capable, the 2nd mostly with skills.
Feats go like this
Level 1 Spell Focus Conjuration- pre-req for the next 2, does little by itself.
Level 3 Augmented Summong- Summoned creatures get +4 Con & Str
Level 5 Superior Summons- If more than 1 creature is summoned, incr the no by 1
At level 4 you get the 2nd level spell Summon Eidelon.
At this point, you have a combo for an unusual combat strategy. Most Summoners prefer to have their eidelons there at the start of a combat, except sometimes master summoners. My Gathlain does not for tough fights.
The strategy is- Round 1 cast Summon Monster 3 as a SLA [ I can do it 7 times/ day] calling 1-3 monsters from the Summon Monster 3 list. You get an extra 1 unless you roll a 1, and the buff to str and con.
Round 2 cast Summon Eidelon calling 2 Eidelons. You get an extra Eidelon as you have summoned more than 1 creature , and the buff to str and con on all 3.
Round 4 Buff Eidelons and self.
Round 5 As most of your 1st summoned monsters are now dead, cast summon monster 3 again.
Collect treasure and bask in the grateful awe of your fellow PCs.
I am near certain it's 100% legit.
It is not w/o downsides, you don't always know when the fights are coming, you have nothing there at 1st and the Broodmaster's swarm of smaller weaker eidelons is not normally as good as 1 monster. And it chews up every feat.