Overwatch 2

Overwatch 2 Solution

What does Resurrect do?

Resurrect is bound to Mercy's Secondary Fire which is by default.
Resurrect allows Mercy to bring back one (and only one) ally back from the dead. She must be in a 5 meter radius of them, have line of sight, and must resurrect them before they respawn (10 seconds). Resurrect has a cooldown of 30 seconds. It has a cast time of 1.75 seconds and reduces your speed by 75% while casting.
Souls are dropped at the position of allies which allows you to get to them quicker with Guardian Angel (Ability 1, by default). This also works with allies that are living.

What does Valkyrie do?

Valkyrie is bound to Mercy's Ability 3 which is by default.
Valkyrie, according to the description, enhances her abilities for 15 seconds. But what exactly does that mean? Here's a list:

How do I unlock Huge Rez?

Play safe. You're going to want to stay behind and rez when you can, but be careful if a rez is too deep. Intentionally not healing an ally that is close by can net you an easy rez (and it brings them back to full health too!)

You want to be careful of enemy ultimates, especially Soldier: 76's Tactical Visor and Cassidy's High Noon as they can swat you out of the sky in an instant. Flankers like Genji and Tracer can also cause problems when trying to stay back, so knowing where the nearest health pack is located is helpful.

Boosting Methods

The Lockdown Method

This is the most common method to boost Overwatch that requires 10 people.

1. Get a group of 10 people.
2. Get into two groups of 5
3. Disable cross play
4. Queue for Quick Play Open Queue at the same time and hope it matches you guys up
5. Once you match up, have the opposing team kill your teammates and then resurrect them. Do this 5 more time to unlock the achievement.

Remember to keep the objective contested unless it's a Control map which will not need contesting unless someone captured it.

Not a complex one, but just in case you need help: Like a lot of the achievements in here, there's a bit of luck with this one. I kept getting the Revive x3 to appear, but couldn't get the x4. What eventually worked was playing on an escort level. The payload was approaching the final destination, and I had my rez. I listened for an opposing team ult (in this case, D.Va), and ducked out of the way. After the rest of the team wiped, I hit to fly to them, and rezzed everyone. Again, this takes a little luck because if your team is paying attention a lot of times they won't get killed by by the ult. But in the final payload push moments, people become more desperate and risk more. Good luck.

Sorry if this doesn't help. I saw there was no guide yet and just wanted to offer a hand if possible.

EDIT: Additional info from CR4SHED:

- Resurrect only works within 10 seconds of an allies death.
- Resurrect currently has a range of 15 meters.

OUT OF DATE INFO. UPDATE COMING

Mercy's Resurrect ultimate ability allows bring your teammates back to life if they are within range. Dead teammates will appear as yellow skulls on the battlefield with a circular timer showing when they will spawn.

We will need to resurrect 4 teammates in one activation of our ability.

I recommend going for this while attacking the payload and having multiple enemies on the objective at the same time. Stay back and wait for your teammates to get taken out (probably by an enemy ultimate), and then fly in range and use the ability.

If you can get a total of 4 resurrections at once, you will unlock the achievement.

If you'd like to learn more about Mercy, you can view this video. The achievement is described and shown at 9:51:

I don't know if this will help, but there's a few Quad Rezzes in this video I made. One of those times, I could've got a Penta-Revive but I was too far away to reach the fifth one and I didn't want to die in that little room I was stuck in. Anyway, here's the video, which people apparently think is very high quality. They tell me in person (Party chat). They didn't say it in the comments though, but they said that they loved it. Here's the video.