Rune of Fortification (FoC training)

Another training, and first ever rune suggestion.

Color: Gray, like a metallic rock or something
Particles: Gray spell shield

Effect: Reduces all incoming damage for a duration

Reduction: 65%
Duration: 10 seconds
Notes: Cannot be purged, the damage reduction is not counted armor or magic resistance, and cannot be reduced in any way. Reduces pure damage, but not HP removal.

This is my practice for the FoC, feedback is more than welcomed. And Yzreel, where is the contest???

No clue man, shoulda asked Wulfstan since I had given him the theme I wanted. I think he'll post later tonight, just be patient :p

So give the team that's in the lead basically a free increased version of Ram buff without the later HP removal side effect.
Sounds op? Is op.

I do not follow you. This is a rune, a rune that lasts 10 seconds. A way to survive ganks and diving towers. Why OP?

Give the rune to a tank and dive tier 4 without any worries. 65% Is HUGE especially late game.
Since bottle can be shared the tank can use the bottle for the rune, run in, kill everything, run out and have more than half HP left most likely.

Give the rune to super farmed bristleback, fountain farm without any worries whatsoever.

Also, it seems completely useless without a bottle. If you grabbed it without a Bottle it would probably be gone, or close to gone by the time you reached a lane to gank, or returned to your lane.