What if Season 5 Brought Back Immobile Mid's?

For example, an item like this (And for now I'm just gonna slap a name on it)

Cloak of Magus 70 AP 400 Health Unique Passive: Upon taking damage from an enemy champion, this unit gains 2% bonus movement speed. This speed is increased by 2% for every 1% of health missing. Unique Active: Instantly gains 200% bonus movement speed for 2 seconds. Passive is disabled while on cooldown. (60 second cooldown)

Recipe - Giants Belt - 1000 Blasting Wand - 860 Recipe Cost - 440

This item would be beneficial to many AP mids with no mobility because it makes it easier for them to catch out an enemy, it offers a little innate defense, and it isn't too overwhelmingly strong, because the active would allow the ability to follow up on ganks, or even make an engage if your team doesn't have a proper one.

Or maybe even buff Rylai's so that instead of simply slowing the target, hitting a champion with a spell would slow them, and and steal some of that movespeed for themselves. It's kind of like Trundle's spells, but for movement speed.