The idea comes from the mass effect 3 multiplayer, the players were given expendable 1 time use "first aid" kits that repaired your shields and health to full instantly, with a limit to how many you could use in a match. Obviously that would be a little overpowered, but something like a heavy shield capacitor or built in nanomachine self repair unit that takes up your grenade slot, could be put on a timer or one time use (not replenishable by nanohives or supply depot like grenades). The shield capacitor could instantly recharge a set amount of shields, while the repair unit heals a set amount of armor over a short time.

This basic concept would be good to start with, no need to get too complex but other ideas might be to bring the shield recharge delay to 0 a few seconds after the capacitor has been activated; even if you're being shot at your shields will recharge at the rate they normally would. Maybe repair unit could also modify your natural self repair rate for a short time, for example if you repair your armor at 10hp/sec, after using the module it may jump up to 20 hp/sec for 10 seconds along with the initial burst of armor repair, or maybe have a variant that just multiplies your natural armor repair rate for a set amount of time.

Obviously the concept is simple, you get into a tight spot, you tap that button and give yourself an extra few seconds to attack, hell alot of us start chucking grenades when we know we're going to die anyway, why not make that button actually useful?

Thoughts?

Lol alot of the people I used to play with are getting back into me3, won't last long because there's nothing new anymore, but it is still fun and I wouldn't mind getting on again once in a while :)