Blood Summon

You can summon a small living creature for a limited amount of time using another target creature's blood (you can use your own blood - does not use blood orb stack*). Maintaining this too long can cause the target to faint from blood loss and failing to call back the summoned creature or letting it get destroyed will cause the target to take 10 damage from blood loss. 

The summoned creature has a physical form, so it can carry objects or interact with its environment in a logical way depending on the creature's form. 

(a double can be, for example, a dog, a frog, a bird or any other small creature nearing a small dog's size)*