Hunters have been taught a magical brand to bind a Beast's Essence that they have successful tamed.

This branding binds the tamed Beast's Spirit to the caster's Spirit.

When the tamed creature dies, it's Body vanishes into the Fey, following its master, awaiting its master's call.

The default amount of Summons a creature can have is 3. This can be increased using the Feat Studies in Summoning. When creating a new character beyond first level, the GM can create your Summons he thinks you have tamed, and attach you to them.

If the Hunter dies, his Summons in the Fey become unbranded, and wander the Fey. If they are alive, and still in their non-native Plane, they also become unbranded, and could go hostile, but this is up to GMD depending on the Encounter.

GM Note:
While the tamed beast's Spirit is in the Fey, it can be seen, and targeted by creatures who have Truesight. Spirits are very Vulnerable to Suggestion and being sent to the afterlife while in the Shadow Ambusher Plane; they technically have 0 Vitality, and have DIS to all Charmed effects. The Game Master can determine these special circumstances if this effects the Encounter in some way.