D.Va has been a staple tank of Overwatch since her Defence Matrix was changed to an ability that could be toggled. The ability essentially allowed her to delete almost all damage output from the enemy when active. Defence Matrix allowed D.Va to shutdown the best dps players and vaporise countless ultimates. This unprecedented utility is receiving a huge nerf as the Defence Matrix's energy drain is being doubled, thus decreasing the uptime of the defensive ability by 50%.
This change will be met by cheers from dps mains who have had games ruined by this one ability, but will severely frustrate the D.Va mains who enjoyed the power of it.
Blizzard are, however, compensating D.Va mains with a brand new offensive ability. D.Va will be getting Micro Missiles, an ability which allows her to shoot small missiles that explode on impact, dealing damage in a respectable radius. These missiles can be combined with her primary Fusion Cannons and when in flight with her Boosters, which are also receiving a buff as she can now shoot her Fusion Cannons when flying. Her Micro Missiles sound similar to Soldier 76's deadly Helix Rockets, which means that she will, likely, boast more burst damage with these projectiles.
The updated D.Va will be available in the PTR soon.