Just helps to get the fundamentals of the mode. Square Enix has their own little Feast guide, which gets regularly updated about the rules in there.
https://eu.finalfantasyxiv.com/lodes...sden/thefeast/

Ofc some parts of it like PvP Custom Matches or how to use the camera in spectator mode aren't really needed to play it. But it tells you for example that Feast Training Mode is possible to queue as a duo. That could already mean that you faced a premade duo team in the enemy group, which makes it way harder to win if they are experienced.

The invite link for the PvP Feast learning/chat discord is https://discord.gg/sUy86UC . But because of the recent changes there won't be any updated class guides yet, as we still wait for the update in 5.05 or 5.1. However there are question channels for tank and paladin, there should be some useful information about it.

Because of the current meta, tanks are not as tanky anymore and have trouble stopping bursts. Cover on Paladin is pretty risky too, the already high bursts get an additional 20% dmg boost, which makes it difficult to heal without any mitigation tools besides hallowed ground. Be aware if you play the melee role, people will expect you to lead the match sooner or later by calling and preparing targets and starting countdowns.