There are some experimental changes happening with Roadhog at the moment on the Public Test Region - one of which involves his heal, which now reduces incoming damage by half during its use. As Reddit user "JJFreshMemes" discovered, this now means that he can tank a D.Va explosion point-blank and survive.
D.Va's self-destruct, the ultimate with the highest base damage in the game. It deals a whopping 1000 damage, which is almost twice of Roadhog's normal 600 health bar. With the damage reduction, however, it only deals 500 - giving Roadhog 100 health remaining to survive the blast.
This makes Roadhog the first character able to survive the explosion without the use of an ultimate or a shield. On top of this, it makes the play of pulling an exploding mech away from a team with a hook a viable strategy, as you will no longer have to sacrifice your life to pull it off.
It'll be interesting to see if this change makes it to the live servers or if Blizzard decides it is too overpowered.