Mercy's resurrect ability has been the subject of much debate in the Overwatch community over the last few months. First it was too powerful but unfun, then the new single-target Rez created its own set of problems. A nerf in November added an interruptible charge-up time to the ability, but even that wasn't enough to stop her from being the by-far most-picked hero in the game.
Now, another nerf is on the horizon, this time to her new Ultimate ability Valkyrie. On the Overwatch public test realm, Mercy's Valkyrie now only lasts 15 seconds (down from 20). It also no longer grants an extra charge of Resurrect or remove its cast time. The speed boost that Valkyrie grants to Guardian Angel has also been decreased by 50 percent.
In other words, Mercy's Valkyrie Ultimate is now primarily about giving her flight and healing/damage beams that link to her allies. Resurrect is pretty much unaffected by popping her Ult.
"Mercy’s recent Resurrect changes have helped in allowing enemies to have more counter play in dealing with her, but she was able to use Resurrect through Valkyrie enough to largely mitigate the impact of the previous changes," read the developer comments. "Additionally, we’re toning back the amount of mobility Valkyrie provides through Guardian Angel and reducing its duration to overall reduce the power of this ability."
Junkrat, the other super-popular hero of the month, has also received a small nerf. His Concussion Mine's damage now has significant falloff if it doesn't hit the target directly. It still deals 120 damage on a direct hit, but that damage goes down significantly as you move away from the center of the blast. Previously, the full 120 damage was dealt to anyone within the blast radius.
"Junkrat has been enjoying the flexibility his double-charge Concussion Mine provides, but it has now become a bit too easy to throw out huge bursts damage in a large area," Blizzard said. "With this change he can still dish out similar damage but he must now be more accurate with his tosses."
As always, updates on the PTR are subject to change. In fact, Blizzard even specifically pointed out that it will likely be iterating on these changes in the coming weeks.