ezreal new item

So, players are devided into two groups: ap ezreal, OR ad ezreal so i thought of a special item that ezreal would buy one time in a game, wich makes all of his abilitys to do magic dmg if he is going ap, OR makes them do ad dmg if he is going ad, and that would make ezreal stronger and also more fun to play, making him powerfull either ap or ad. i would like if a rioter would answer this thread and tell me what is wrong with my idea.