Summon
Term
A 
Summon is a broad term for any creature controlled by another creature.
In Alternating Initiative 
Summons go last, and alternate between Player Characters and NPCs.
Summons also do not get 
Dying Stratum Rolls, because they are considered a creature, and are 
Dead once their Vitality reaches 0.
If the Summon is called from another Plane of Existence, when it reaches 0 Vitality on a non-native Plane, it re Turns back to its Plane usually with 1 Vitality. If the Summon dies on its native Plane, it is considered Dead.
The default amount of Summons a Caster can control, of any Summon type, is 3. This can be increased by using the Feat: 
Studies in Summoning.
