Your familiar has a link to your soul. You can protect an ally from damage with your familiar, but you are going to feel it.

Daily   ✦     Arcane
Immediate Interrupt  

Requirement: Your familiar must be in its active mode.

Trigger: An attack hits an ally you can see

Effect: Your familiar can shift its speed; if it ends this movement adjacent to the triggering ally, the triggering attack hits your familiar instead of the ally. You take damage equal to your level.

Published in Dragon Magazine 386, page(s) 22.