Elemental swarm

Elemental Swarm is a conjuration spell that summons 2d4 Large and 1d4 Huge elementals whose element depends on the plane from which they are summoned. Its descriptor when cast is the same as the element of said elementals.

Effect
This spell opens a portal to an Elemental Plane. A druid can choose which plane (air, earth, fire, or water); a cleric opens a portal to the plane matching his domain. You can then summon elementals from that plane.

When the spell is complete, 2d4 Large elementals appear. Ten minutes later, 1d4 Huge elementals appear. Ten minutes after that, one greater elemental appears. Each elemental has at least 5 hit points per HD (that is, at least 60, 80, or 100 hit points, respectively). Once the elementals appear, they serve you for the duration of the spell.

The elementals obey you explicitly and never attack you, even if someone else manages to gain control over them. You do not need to concentrate to maintain control over the elementals. You can dismiss them singly or in groups at any time.

When you use a summoning spell to summon an air, earth, fire, or water creature, it is a spell of that type. For example, elemental swarm is a fire spell when you cast it to summon fire elementals and a water spell when you use it to summon water elementals.