#1 - April 20, 2016, 7:33 p.m.
Most creatures you'll encounter will now allow up to 5 players on their tap list by default. The mob's name will grey out when you can no longer obtain credit for attacking it.
Parties are a special exception, as we allow your entire party onto the tap list if one person is on the tap list. Please let us know if you find bugs with this, we want you to be able to progress with your group.
Rare spawns, world bosses, and quest bosses will largely continue to allow unlimited tappers, as they have been previously, both to facilitate large group engagements and to remove potential roadblocks.