Some exceptions may apply
Earlier this month, Rivals of Aether II announced their set of guidelines on new character releases and balance changes with respect to the tournament legality of said characters and which versions should be played at competitive events. As it happens, Frosty Fausting will be the first major event where these rules will be tested.
Today, the organizers behind the event have confirmed that the Rivals of Aether 2 tournament will be running the latest patch, as well as Etalus, with the main caveat, as requested by developers, of the playtester being barred from using the character in the tournament. The organizers will also publish a more detailed ruleset closer to the event.