Reducing HP by 10% is not a good idea as it is

[Yup]

I agree, ^ at the bare minimum, Perfect Immunity should protect

Well I can see an argument against immunity, perfect or otherwise. I mean, it's technically not a buff. Although, I'm not opposed to immunity preventing it

The thing is... if no damage can be done due to a buff... then how is damage being done??? It's not logical that invisibility and invincibility don't prevent the block.