League of Legends Reforged Rune: Glacial Augment
Glacial Augment

Immobilizing an enemy champion will cause 3 glacial rays to emanate from them towards you and other nearby enemy champions, creating icy zones that slow enemies within by 30% (+3% per 100 ability power) (+4% per 100 bonus attack damage) (+9% per 10% heal and shield power) and reducing their damage by 15% against your allies, excluding yourself, for 3 seconds (+100% of the immobilizing effect's duration).
Cooldown: 25 seconds
Rune Path

Inspiration
freeze ray with.
Tip: When you have the rune equipped the game will add an "Active Slows" box to the recommended purchases (similarly how it does with Masterwork Items for Ornn) which will have every item that is affected by Glacial Augment.