Stormraiders Surge procs off shield damage, not specifically HP?
I got pumped on level 1 by Darius after he procced SRS by just hurting me through my shield as Shen. He didn't do 30% of my life so I was super surprised and lost lane off of it. Is that intended? The mastery itself says dealing 30% of a champions max health will activate the buff. Can show the clip of it if necessary