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.
Edit: they're not too hard solo.