What does Coalescence do?Coalescence is bound to Moira's Ability 3 which is 
by default.Coalescence shoots a beam that can both heal allies in the beam or damage enemies in it. It extends 30 meters in a straight line and cannot go through walls, but can go through barriers. It heals/damages 140 health/70 damage per second and will passively self heal you for 50 health per second.
Note: This is a channeled ultimate which means that it can be shutdown by abilities such as Roadhog's Chain Hook and McCree's Flashbang.
How do I unlock Antipode?You must hit 7 targets at the same time. Since it can hit both allies and enemies, any combination of targets work.
Zarya's Graviton Surge is the best way to go about getting this achievement as it groups up either your allies or your enemies. Additionally, choke points or small rooms can lead to a 7 person Coalescence, but will be very hard to do.
Note: There are reports of the ultimate not needing to hit all 7 targets at the same time just during a single use. When I was in a boosting session, this didn't work, although there has also been reports that allies need to be damaged in order to be "hit" which I believe we did not do before lining up.
Boosting MethodsThe 6 Stack1. Get a group of 6 people.
2. Enter a game as a team and have 2 people choose Moira and Zarya. The other people can be whatever they want, but a suggestion from me is a Mercy or Ana to help with the healing and maybe a Sombra to stop people from escaping the Graviton Surge (if the enemy team has a counter).
3. Build up Moira's and Zarya's ultimates.
4. When Zarya gets a successful Graviton Surge with 2 or more enemies, have Moira use Coalescence on the Graviton and have the team stand in the beam* (2 enemies + 5 allies = 7 targets).
The "Guaranteed" Achievement1. Get a group of 8 people.
2. Have everyone add each other as a friend in advance.
3. Enter a game as a three stack and have the other 5 people spectate off of them from the social tab (make sure to select "Join Game" and not simply "Spectate"). As people leave, the spectators will take their place** and having the spectators join as described means they won't be kicked in between games.
4. As soon as you have all 8 people in the game, line up and let Moira use Coalescence*.
The Lockdown MethodThis is the most common method to boost Overwatch that requires 12 people.*** Spoiler - click to reveal ***1. Get a group of 12 people.
2. Have everyone add each other as a friend in advance.
3. Enter a game as a three stack and have everyone else spectate off of them from the social tab (make sure to select "Join Game" and not simply "Spectate"). As people leave, the spectators will take their place**. Having the spectators join as described means they won't be kicked in between games.
4. As soon as you get a person both sides, communicate to see how much people should be spectating both sides (i.e. how many randoms are on each side).
5. Once the lobby is full with all 12 people, have 7 people line up and let Moira use Coalescence*. Remember to keep the objective contested unless it's a Control map which will not need contesting unless someone captured it.
TROLLING CAN GET YOU BANNED IF YOU GET REPORTED. BEWARE OF THE METHODS YOU USE TO GET RANDOMS OUT OF THE LOBBY.
*I suggest Moira to not move her beam and instead allow everyone else to walk into it.
**Spectators will only fill allied spots.