Weird random crazy Thornmail idea

Okay, so here it is.

What if Thorn were reworked as an armor counterpart to Wit's End?

As in + +

The total armor would drop a bit, leaving Frozen Heart as the highest armor item in the game. Aside from the passive it has now, Thorn would also deal magic damage OnHit equal to some percentage of your bonus armor.

Pros -Thorn is no longer purely passive in nature, but rather makes you an active threat. -Amazing synergy with Wit's since the passives of both items improve the other. -Makes heavy Fighter-y folks extra scary. -New Thorn becomes attractive to a MUCH wider range of champions beyond Ram/Taric/Malph/Leona/Galio.

Cons -Less raw armor on Thorn makes Rammus a sad armadillo. -Item gets more expensive.