Purification Beads is an active item that "removes crowd control effects and makes you immune for" a second or few. Each tier costs 300 gold and each largely only reduces the cooldown by 45s. Does buying subsequent tiers affect the cooldown if it's already cooling down? What about any other active items? For that matter, what about Skills?
Cooldown reduction affects concurrent cooldown
smite
Best Answer
Based on Purification Beads, no, acquiring cooldown reduction (CDR) does not affect the cooldown of abilities that are already on cooldown; the cooldown reduction only applies after it has cooled down. This means that it may be better to buy all tiers of Purification Beads before popping them, and similarly with other forms of CDR, like the jungle mana/CDR buff.