I guess if you were really wanting Immortal you could bring 4 tanks for KT and have the 3rd OT build threat on all 4 guardians.
Immortal/Undying is based on killing KT with a Raid ID where 0 deaths are recorded. So, once your guild has Immortal/Undying, you could theoretically sell spots for the KT kill--probably for a really solid chunk of money.