Erollisi Marr on live had Trakanon and Venril Sathir both on rotation before Velious launch, and it lasted about another year afterwards. All you had to do to enter the rotation was kill the mob, and most guilds would allow you the opportunity to try.
NToV was treated the same way, not necessarily a rotation in that case, but the guilds had respect for each other - whichever guild could down Aaryonar first had the rights to kill the wing, until the next Aary spawn.
System that worked out very well, I don't recall too many flames about it.
Just an idea, from a p99 newbie
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