uncommon cantrip evocation summoner 

Cast [>] verbal

Range 100 feet; Targets your eidolon

Duration 1 round

You focus deeply on the link between you and your eidolon and boost the power of your eidolon's attacks. Your eidolon gains a +2 status bonus to damage rolls with its unarmed attacks. If your eidolon's Strikes deal more than one weapon damage die, the status bonus increases to 2 per weapon damage die, to a maximum of +8 with four weapon damage dice.

Secrets of Magic, page 144.