Even though the majority of raidwide damage Felmyst does is nature based the resistance that will help you most (and one you should use at least while learning) is Arcane. The incoming Nature damage is low and predictable. The Encapsulate damage (which is Arcane based) is rapid, random and affected by normal resistance rules. For that reason, during the learning, everyone should use their Violet Badge and plenty of Major Arcane Protection Potion. Ground Phase Flight Phase Rinse and Repeat. You have 10 minutes. A well-geared group can down the boss before a third flight phase.