With patch 7.0.3 Blizzard changed the way you transfer from realm to realm when joining a cross realm group. In patches 6.2.4 or prior, there was a global group transfer, where you would change your realm depending on the current realm of the party. If a group was on Sunstrider realm and you joined that group, you would be transferred to the Sunstrider if you’re not in combat.
As Garrosh said to Gul’dan: “Times change.” With Legion release there’s a new rule: the first person from the party, who enters the zone, will mark that zone for its player’s realm.
What that means:
Zones are now independent and you change realms in there depending on its current flag. Flag is put once a player is in a group and enters a zone. Flag is being removed when all players leave that zone.
You’ll be transferred if you’re in a zone, and you join a party with a player already in that zone.
You’ll be transferred if you enter the zone’s by crossing its border and there’s already a player from your group in that zone.
You’ll NOT be transferred if you enter zone if no other player from your party is there.
Even if you’re not a leader, if you were the only person from the group in the zone and another player from that group comes to that zone, he will be transferred to your realm, since you’re the first person, who entered that zone while in a group.
Detailed example:
Charlie-Killrogg decides to kill a rare monster in Talador. He lists a group in the Group Finder and waits near the rare. When he listed a group, he formed a party. Since he’s from Killrogg and he’s in Talador, system assigns for that party version of Talador from Killrogg realm.
New player enters the party: Bob-Outland. Bob is now in Winterspring. He’s the first person in this party, who’s located in Winterspring. If it was 6.2.4, Bob would be on Killrogg’s version on Winterspring. In 7.0.3 Bob won’t be transferred anywhere, since there’s no flag for Wintersping in Charlies and Bobs party, so Bob flags Winterspring as an Outland’s realm version for their party. Charlie doesn’t understand yet that he’s not going to be transferred and stays in the party.
Here comes Andrew-Ysondre. He was hopping and found a group of Charlie. He expects to be placed on Killrogg, since Charlie is from that realm. But Andrew in now in Tanaan Jungle and other party members aren’t there, so he won’t be transferred, and instead, same as Bob, he’ll just mark current zone. So now Tanaan Jungle for that party becomes a version from Ysondre.
Another hopper comes in, that’s Mark-Balnazzar, he is expecting to visit Kilrogg realm, right now Mark is in Tanaan Jungle. Since Tanaan Jungle is already marked as a Ysondre version, Mark will transfer to Ysondre instead of Killrogg.
Andrew-Ysondre leaves. There’s only Mark-Balnazzar in the Tanaan Jungle. He won’t be transferred back to Balnazzar, because the flag is still there. If a new player joins this party and enters Tanaan Jungle, he’ll be transferred to Ysondre.
Bob-Outland leaves. There’s no one in Winterspring. Flag is being removed. If a new player joins this party and enters Winterspring, he won’t be transferred.
Charlie-Kilrogg is tired of waiting and decides to go to his garrison. He uses his Hearthstone. Talador no longer flagged.
A new player: Simi-Onyxia joins the party. She’s in Talador. Talador is now flagged as Onyxia. Simi doesn’t notice any difference, since she wasn’t transferred. Also, there’s no rare on Onyxia realm.
A new player: Jeffrey-Thunderhorn joins the party. He’s in Tanaan Jungle. But there’s still Mark-Balnazzar there and Tanaan is being flagged as Ysondre. So Jeffrey got transferred to Ysondre and starts flying to Talador.
Charlie-Killrogg flies back to Talador. But it’s not Killrogg (where the rare was) anymore, it’s Onyxia. So Charlie is now on Onyxia. Jeffrey also left Ysondre when left Tanaan Jungle and entered Onyxia's version of Talador. Three of them is now standing in front of the spot where rare spawns, but it’s not there.
All three of them leave. Charlie-Killrogg is now being transferred on Killrogg in Talador and sees his rare. Simi-Onyxia is still on Onyxia and wasn’t transferred anywhere. Jeffrey-Thunderhorn is now being transferred to his version of Talador on Thunderhorn.
That leaves Mark-Balnazzar in Tanaan Jungle on Ysondre the only one in party. Mark is being transferred to Balnazzar’s version of Tanaan Jungle.
Mark leaves the party. Party information has been removed from the servers.
