Prolonged Summons (Feat)
Your summoned creatures are bound to this plane for longer than normal.
Prerequisites: Level 26, Summoning Perfection (Feat)
Related: Summon Companion (Feat)
Benefit: Whenever you summon a creature or creatures with a summon spell you cast yourself (which may include the use of a magic item), the summoned creature(s) remain in your service for longer than normal. Rather than vanishing at the end of an encounter, they persist for up to 24 hours or the summoner's next full night's rest, whichever comes first, unless the summoned creatures are killed, dispelled, or banished. In addition, as long as the summoned creature(s) survive an encounter, they fully heal themselves between encounters automatically.
Special: A Druid of at least 26th level may take this feat even if they do not have the Summoning Perfection (Feat), and may apply its effects to their Animal Companion. If they also wish to apply it to any summoned creatures they cast themselves, they must meet all of the listed prerequisites as normal. When applied to their animal companion, the animal companion fully heals itself between encounters automatically, assuming it survived the encounter. Applying, changing, or removing the effects of this feat may only be done after a full night's rest, and once applied, the effects persist until removed. Only one Summons-based feat may ever be applied to an Animal Companion at a time.
Generally, there is no limitation on how many Summons-based feats can be applied simultaneously to a summoned creature (or creatures) that you cast yourself, other than the number of Summons-based feats you actually possess. The caster can choose to apply (or not apply) each feat (or all such feats) at the time the summon monster spell is cast. However, some feats specifically list other Summons-based feats that they are incompatible with. In such cases, only one of the conflicting patterns can be applied.