Would a Feat that made enemy movement cost double when within 5ft of the player be too strong?

@astibogaWould a Feat that made enemy movement cost double when within 5ft of the player be too strong? bns action or action to activate? I think that would be a really cool feat, esp for games that use minis and grid #WOTCstaff

— (((Mike Mearls))) (@mikemearls) August 1, 2016

@astibogaWould you feel it would be too powerful if constantly active? Maybe make it a bonus action to activate? it really depends on campaign, but if you use minis/tactics I'd make it apply only to enemies you made a melee attack against

— (((Mike Mearls))) (@mikemearls) August 1, 2016

@astiboga hit or miss, you disrupt them and they move slower while closer to you

— (((Mike Mearls))) (@mikemearls) August 1, 2016