Feat that lets you summon 1 fiendish and 1 Celestial

[Dormammu]

I can't find this feat, it was something like, "when you summon multiple creatures you get one celestial & one fiendish"

Anyone remember what this feat is called?

[Samalpetey]

Closest I see is balanced summoning (http://www.d20pfsrd.com/classes/core-classes/wizard/arcane-discoveries/arcane-discoveries-paizo/balanced-summoning), but it's an arcane discovery, not a feat

[Dormammu]

[I]t's an arcane discovery, not a feat

That would explain why I was having a hard time finding it.