Hextech Starburst - aka turn every AP mages into mini-Leblancs
Yeah what more can I say... this item literally breaks the rule of LoL. Considering how back in beta and early Seasons flash has been nerfed more than 10 times, yeah... let's introduce an item that provides flash with a measly THIRTY second cooldown, along with above average stats like AP and cooldown reduction.
In DOTA Blink Dagger costs 2000 gold, and it ONLY provides the blink and nothing else. Here you have a solid item that also provides a champion with a gap closer or escape.
Imagine Syndra, Veigar, Lux, Annie, Xerath with a dash/escape. Yeah... scary.