Extra Summons (3.5e Feat)
From D&D Wiki
You may use your Fiend Summoning ability two extra times each day.
Prerequisite: Must have the signature summon ability of the great Fiendish Houses
Benefit: Your summon ability may be used two extra times each day (the ability is normally usable once each day, so it could be used for 3 separate chances to conjure a fiend).