Give Dva something like 200 ammo for example.
Each primary fire costs 5 ammo.
Each second of defence matrix cost 50 ammo.
Has a 3 second reload time.
Dva has up to 4 seconds of DM again, but sacrifices damage if using it.
Dva players need to manage their ammo like most other heroes.
Also revert DM cooldown back to 1 second.