The main reason immovable is slightly overpowered is that its stamina cost is a bit too low for its duration now, it mitigates some of the weaknesses of light armor, and because regular CC break has a "break free" animation that is kind of like a self stun, and you can avoid this by keeping immovable up permanently.
Classes that are running shield stacking (class shield or healing ward + harness magicka) and immovable on top of it are a bit too tanky. Shield stacking in itself is strong, but when you throw immovable on top of it -> even if you drop their shields they have stronger armor/spell resist than they should and CC immunity on top of it.
I think immovable needs to be slightly adjusted otherwise shield stacking and immovable will become the meta.
Ali Dreadsabre -Necromancer
Ali Sabre -Nightblade