Idea for a new ap item

250health 70ap 50armor Unique Passive: Damage taken from nearby allies excluding yourself is added into a pool, after a certain amount of damage is taken( Damage needed to be taken increases with level). After the cap is reached all allies recieve a small % of the damage taken as additional damage that goes toward spells and auto attacks that does magic damage and lasts for 8 seconds. 120sec cooldown

Let me know your thoughts below and if you think something should be changed about this or have your own ideas post them down below.