Okay, maybe her recent buff may influence her play, but I have seen other, far more important ways Mercy will return to the meta. Blizzard has realized how underpowered she has been in recent times. Previously, Lucio and Ana were pretty much the only ones played. While they did buff Mercy, it is the subtle changes in other heroes which make her more viable. The biggest change is Sombra.
I was watching this video by L0ne Hawk when it came to me: https://www.youtube.com/watch?v=Gaz78vz_GwU. In the video, new synergies were discussed regarding Sombra. A huge one that seemed to be very popular back in PTR is Zarya and Sombra. In this synergy, Zarya would use Graviton Surge, and then Sombra would EMP the floating heroes awaiting their doom. This could either lead to another Ult to combo with or just some simple focus fire. Since I am a pretty decent shotcaller, I tend to habitually think about counters and counter picks.
I will not delay the obvious. Mercy is screaming to be selected right now. A good Mercy is supposed to read the play and make the quick decision whether to be in the group or not. That is why when playing against a good Mercy, she will come out of nowhere while your team is searching for her, but why is this more important now than before?
There is no other practical way to stop this combo from occurring. If this combo becomes meta, we should be seeing a lot of Mercy. Just think about what EMP does. It blocks off all abilities including ultimates. One would think this would be unstoppable. No shields, no ability heals, no ultimates can be used. Heroes such as Lucio (who was heavily nerfed) and Zenyatta (who cannot even heal when hacked) would not even be able to use their preventive ultimates. In addition to that, even if Lucio does get his soundbarrier off before Sombra EMPs, it will not matter because the sound barrier is removed when EMP'd. As for Transcendence, everyone knows that a logical team can use Ana's grenade to simply negate the transcendence almost entirely. Mercy, however, would be away from the group. She would wait and swoop in like she usually does when played, and can be the only practical counter to this synergy. This would also leave your team at an ultimate advantage because they used two or three while your team just used a rez (which is much easier to get). Of course, there are other ways to block this such as having the Lucio hide or a Mei for her wall if they can read the play well enough, but these are heroes that tend to be with the group, not away from it.
Another way Mercy can return is the Mercy plus Soldier synergy. Soldier has been seeing a lot of play recently, and he has become quite the powerful hero. His ultimate is almost too good. Once the enemy's Rein shield goes down (as it is now easier to do so), he can pop that bad boy and do some gruesome damage. Now add supports to this mix, and there is a recipe for disaster. Mercy can damage buff while Ana gives him nano boost. A humble cost of two ultimates for a possible team kill. I can definitely see Soldier, Mercy, Ana, Sombra, Dva, Zarya being a valid team comp in due time.
Of course, I could be all wrong about this, but it just seems to make sense and fit in perfectly.
Hope this post helps bring some new ideas.
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