Extremely skill-based item?
The gist of it would be having an active that can create a spellshield instantly without a channel time, but it only lasts like 0.05-0.1 seconds or some incredibly small duration. Cooldown would be something like 90-150ish.
Essentially a one-time Fiora Riposte, but on a MUCH smaller window of usage. It would have to be timed perfectly, but would reward said good play in return?
If it's too much though, it could be maybe balanced by a self-imposed silence and/or blind for like 0.5s from the start of item usage to prevent instant retaliation through abilities which would be unfair (maybe? I dunno), but it would allow for escape perhaps.