Conjurer ACF

[Zom B]

Elemental Seed: Your summoning spells are seeded with a specific element before they have been cast. Select an element type (Air, Earth, Fire, Water). Your spells with the [summoning] descriptor also gain the selected element as a descriptor so long as they can summon a creature with the selected element as a subtype. Select another element from the list to be your "banned" element. You may not summon creatures that have this element as a subtype.

Essentially, the idea is to allow the spell to benefit from feats and abilities that enhance your spells with a certain elemental descriptor, and to allow reserve feats to work with summoning spells.