League of Legends Reforged Rune: Guardian

While within 350 units of an allied champion, you raise your Guard. Allied champions you affect with unit-targeted abilities are also Guarded for 3 seconds, regardless of distance.

If you or a Guarded ally would take damage within 2.5 seconds or lethal damage from an enemy champion, monster or turret, you both first gain a shield for 2 seconds. Guardian only goes on cooldown when the shield is triggered.