PFSRD:Improved Spell Sharing
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Improved Spell Sharing (Teamwork)
Your link with your companion creature allows you to share your magic with it.
Prerequisite: Ability to acquire an animal companion, an eidolon, a familiar, or a special mount.
Benefit: When you are adjacent to or sharing a square with your companion creature and that companion creature has this feat, you can cast a spell on yourself and divide the duration evenly between yourself and the companion creature. You can use this feat only on spells with a duration of at least 2 rounds. For example, you could cast bull's strength on yourself, and instead of the spell lasting 1 minute per level on yourself, it lasts 5 rounds per level on yourself and 5 rounds per level on your companion.
Once the spell is cast, you and the companion creature can move farther apart without ending the effect.