Easy fix would be to make it work like dark sim. By this I mean you have to cast it during their cast. Also like trash said make it only steal the ability for 6-8 seconds.
If they don’t want it to work like dark sim a 1 second cast wouldn’t hurt either. After these nerfs they could reduce the cd to a minute or something to compensate. This way it isn’t nerfed to the ground but has good counterplay.