Frozen mallet needs to be either removed or reworked
Okay so anyone who has played toplane against a rat that throws stuff (
) should know how toxic it is having to deal with the perma slow coming from 
A pretty easy solution would be to make it melee only, but that won't fix the fact that the item will only ever be built on champs who can win duels extremely handily already and are buying this item to make it impossible for their target to run.
What makes this even worst is that, since autos are point and click, it completely negates the need of a champ to actually use their kit properly to secure a kill. If a
gets a stun, or Gnar lands a boomerang, and they get free auto's on me, that's fine, I either misplayed or they played well, either situation should lead to a positive outcome for them. But with a frozen mallet, they can just walk up, auto and can stick on you permanently.
This doesn't just make for a bad experience on the side of the target, it's also less satisfying for the user since its always going to be more fun to use your kit properly to secure a kill than getting it because they can't actually get away. Adding to this it makes balancing these champs incredibly difficult, gnar literally goes from trash tier to insane in days, because if he is strong enough to actually kill you, then you don't have a real chance of getting away.
This item also doesn't really have a healthy use case or even a target group of champs who could potentially want to use it without it being overbearing. Melee carries like
would become impossible to deal with in the 1v1 if frozen mallet was an option for them, and marksman have already shown how annoying they are with this item.
It may seem like this item would be good for juggernauts that want to be able to stick better. Juggernauts are probably the only champs who could ever possibly be healthy users of frozen mallet, but none of them have any incentive to build it.
already have perma slows in their kit and wouldn't really want to build it in any form. 
would rather buy iceborn, and already are incredibly sticky in 1v1's.

use their abilities way more and only auto as a part of a larger combo, and can't continuously stack it. Who's left
?
In my opinion, the entire concept of the frozen mallet is flawed, and should probably be removed, or it should be reworked to become an anti-kiting item because in its current form it just makes top lane less fun every time it pops up.