Shields were already given the ability to affect immortal creatures, I don't think they need a way to avoid their only weakness. Also, I don't like adding even more % chance abilities the player can't see. Like, we already have hax shields now we'd have hax perms haxxing the hax shields.
Maybe you could reword it to lower shields proc chance by 50% or something... but again I don't think Aether's Immortal creatures need shield protection. Maybe this could be in a different element, maybe it could only last for X turns I dunno.
Umm.. I don't wanna be totally negative... the card looks really nice moose. : )