NEW Support Gem: Blade Barrier [suggestion]

Original reddit post is here.

All numbers are subject to ACTUAL balancing if this were a real thing. The point of this post is to showcase the mechanic, not the balance.

EDIT: I forgot to add the 'Melee' tag for the gem.

Design

Purpose of the support is to have an extra defensive option for auxiliary attack skills.
Shield is designed to be reflexive for those "Oh sh*t--" moments, NOT permanent.
Shield activates on attack, NOT on hit.
Could work with melee movement skills.
Shield health functions identical to life, preventing all damage before both energy shield and then life.
Shield buff is called 'Stoneskin' to differentiate from other current forms of shields in the game.
Visual effect/cue on character when shield activates: a quick, semi-transparent barrier flashes in front of your character from top to bottom, before staying as a clearer barrier until buff wears off.
The 'Barrier' tag would be a new classification of support gems and would include the already released Storm Barrier Support - only the highest one of these linked to the top would work on any active skill gem.

Points of note

Shield health is separated into TWO parts: base % and flat additional health. Flat additional health increases as the gem is leveled while base % stays the same all levels. The purpose of this is to tighten gap between low and high life/ES characters, while still incentivizing building life/ES, but not having the tankier characters get out of control if this was entirely % based.
Low mana multiplier as Blade Barrier is mainly gated by cooldown. This is because it is meant to be saved for important times when you know you will soon take damage.
Each point of quality lowers the cooldown by 0.5% up to 10% reduced cooldown at 20 quality, meaning a 4.50 sec cooldown.

Final thoughts

I've always enjoyed using auxiliary skills in PoE, especially powerful ones gated by a cooldown. This was part of the inspiration when designing this support gem. The numbers are still a bit out of whack (the Stoneskin buff should probably only last 1.5-2 seconds, for example) so I'm aware of those issues. Please let me know your thoughts and if you have any questions and I will try to clarify anything I can.

Bump. Thoughts?

Would like to hear people's thoughts on this! :)

I like the concept but just throwing it on a movement skill just means that everyone gets a 1000+ damage barrier. Cooldown only 5 seconds and duration 2.5 means that its nearly always up as you are moving from pack to pack. It's alot of free life just to plop onto a movement skil.

I'd almost rather see this as its own skill instead of a support. Maybe as a spell that scales so you could cwdt it but lower levels wouldn't feel like much but may incentivize leveling up cwdt to get a higher effect.