The tooltip specifically says that it procs 4% on all targets, and 15% on daedra and undead. It is quite a weak skill to be honest, even 15% is way too low, I only use this skill to easier see vampires, I slot it along with Silver Shards on my second bow bar.
Gives your attacks a 15% chance to cause an additional x Magic Damage against undead and Daedra and a 4% chance against all other enemies. Each attack also restores 840 Stamina.
Killing undead and Daedra refreshes the effect's duration.
While slotted, undead and Daedra are easier to see and you gain Major Savagery, increasing your Weapon Critical rating by 10.
The tooltip specifically says that it procs 4% on all targets, and 15% on daedra and undead. It is quite a weak skill to be honest, even 15% is way too low, I only use this skill to easier see vampires, I slot it along with Silver Shards on my second bow bar.
Why magicka damage scaling for a fighters guild ability that restores stamina though?