New Summoner's Rift Summoner Spell: .5 second interrupting snare

A semi-random thought about a way to help balance certain champion matchups. Riot seems to be firmly against adding items that affect the enemy champions and they also like to pretend that champion vs champion matchup shouldn't be decided purely based on picks, so this seems like a reasonable way to customize a champion vs a specific other champion, perhaps if you're counter picked after you pick.

The specifics of the spell: 3-5 minute cooldown (Possibly even 2 minutes depending on how strong it is), single target, instant cast, prevents the targeted enemy champion from moving for .5 seconds and interrupts any spell they're channeling. In other words, its basically rune prison + interrupt.

The idea is to give champions without 'point and click' stuns a way to more fairly fight hyper mobile assassins, and yes I specifically mean Katarina and Leblanc. They're not exactly broken champions but its pretty annoying to hit Kat with a stun when she has 0 cast time instant blinks and you happened to have picked a hero without a fast targeted CC. I think if the numbers are low enough (high cooldown, low duration) then it won't destroy any champion, but it gives you just a little bit of an edge if you take it.

I can't imagine, unless its way over pushed, that it would be selected as anything other than a counterpick to assassins. Lots of champions would love an additional snare, basically any of the melee damage dealers, but most of those are taking smite or teleport right now, and so wouldn't take a combat summoner, as for the rest, I'm pretty sure an ignite doing 300 true damage is going to be more powerful than a very short snare.

In general I'd prefer being able to buy an item that does this so you have more options in game. Right now if their katarina is 10-0 after 30 minutes you don't exactly have a bunch of choices available to you. Build.. banshees veil and hope you still don't instantly die?