What if Flash could only be used offensively?

Flash has always created balance problems in League of Legends, and at one point Riot even considered removing it entirely. The problem with this is that it would create problems for champions like Annie and Alistar, who are almost balanced around the existence of the spell, and it would also remove a lot of outplay potential in the game.

The current state of flash is not entirely healthy for the game though, and the problem is especially bad in pro play, where flash is essentially a "get out of jail free card" on a 5 minute cooldown, eliminating a lot of the excitement that can result from a well-executed gank that would normally kill a player.

The change I propose would try to keep Flash's ability to allow interesting and unique engages, while eliminating or weakening its use for escaping. How it would function is that every enemy champion would have a line drawn between them and your champion, and from that line, angles would be calculated to allow an "area" that your champion is allowed to flash to. In terms of UI, I imagine it would function like Katarina ult or Sona Q, the Flash icon would simply be grayed out when your mouse cursor is over an area that you can't flash to.

The cooldown would obviously need to be lowered since it's not as versatile, and the angles could be adjusted a bit if Flash is too weak or too strong, but as you can see, Flash is a lot less good at escaping ganks, while still being somewhat useful if used properly to dodge skillshots. Annie, Alistar, and Rakan get to keep their sick flash plays, and ADC's have to play a little more intelligently and keep an eye on the map.