The EMP idea is not good because it will render Kira, Bushwhacker, Aura and Proxy’s deployable irrelevant. You’re disadvantaging 4 mercs in game without an equivalent downside. Perhaps you will accept the idea that if Phantom uses this skill, he will be visibly immobilized for 5 seconds? Well it’s as good as putting his pants down for surprise buttsechs.
A reasonable buff is removing the whirring sound of his cloak and retaining his level of invisibility or making him totally invisible but giving him an equivalent louder whirr that can only be canceled by the augment Sneaky. His armor is soft enough to provide him respite from gunfire and because of the inherent hit sound in game, it should be OK.
It’s also not balanced to have invisibility active while performing task like planting or defusing C4, repairing generators or helping someone get up. Come on. Please buff or nerf to balance and not gain player advantage.