Feral Howl

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Prerequisite(s): Shifter, Cha 13+
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Benefit: While shifting, you can let loose a feral howl as a full round action. All opponents within 30 feet must make a Will save DC 10 + one half your character level + Charisma bonus or become shaken for as long as you continue shifting.
 
Source: Unearthed Arcana