i wont go too much in stats because you will say its op anyway 
the idea is to have merc, probably someone like skyhammer (not sure if we want another 120hp firesupport)
and that merc would have something (flare, phone) to call helicopter, and that helocopter would stay on air for few seconds and then disappear (fly away
) and in that helicopter would sit guy that you would start controlling, not sure if there should be mg, some guy with gun or… other merc from your squad! but you wont be able to use their abilities (only shooting) and that merc would be also killable (because heli wont be killable)
soo you could like be skybro and then call your friend vassili that would kill some people for you