
Tar-Tar |
Just to needlessly expound on Cheapy's answer, the Augment Summoning only affects spells. I think this means it doesn't affect the spell-like ability summoners have to cast summon monster, either, since it is not actually a spell (I'm not certain on that point). In any case, it won't help the eidolon - it's only for things summoned by spells like summon monster.

Gilfalas |

Just wondering if the feat works with the synthesis' eidolan.
If you summon the eidlon with the SPELL rather than the class ability then yes for the duration of that spell.
Dev's have posted that it was their intent that it worked with the summon monster SLA for the summoner.
It does not work on the standard summoner class ability to have their eidolon otherwise.

Cheapy |

Thanks for going into more detail Tar-Tar.
The only issue is that you are 100% correct that things that affect spells don't affect SLAs, the SLA that summoners get for Summon Monster is affected by Augment Summoning by explicit designer fiat: here.
This is something that's bugged me for a long time, and I'm quite curious about whether it extends to the other summon affecting feats.

Tar-Tar |
Thanks for going into more detail Tar-Tar.
The only issue is that you are 100% correct that things that affect spells don't affect SLAs, the SLA that summoners get for Summon Monster is affected by Augment Summoning by explicit designer fiat: here.
This is something that's bugged me for a long time, and I'm quite curious about whether it extends to the other summon affecting feats.
Oh, nice! Thanks for the link :)