Lasting Summons (Metamagic)

You can make your summons last for hours.

Benefit(s): You extend the duration of a summoning spell with a duration of 1 round/level or more to 1 hour/level. Creatures summoned this way avoid combat if possible but defend themselves if attacked; if they attack, the remaining duration of the spell changes from 1 hour per level to 1 round per level (so if the spell had 5 full hours left, the creature(s) remain in combat for 5 rounds before the spell ends).

Level Increase: +1 (a lasting summons spell uses up a spell slot one level higher than the spell’s actual level.) You can use Lasting Summons to summon a creature with full duration even in combat, but this increases the level increase of the feat to +3.

Special: A summoner can use this to affect his summon monster spell-like ability, reducing the numeral of the summoning ability instead of increasing the effective spell level.