Lost Ark loves its dungeons and its raids, with most of the endgame content revolving around one or the other. Legion Raids, though, players will need to wait for a little longer to experience.
The major issue the developers have with the western release of the game lies in the fact that Lost Ark's available content is not the same for the western release as it once was for the Korean release. For that reason, they must closely monitor player experience and p[layer feedback, to judge whether to add a certain aspect of the game's content to the game itself.
Per their own admission, the March Update content-wise was a bit early and too close to the game's release itself. To that end, developers will focus on releasing new content, which they label as "horizontal", that is meant for tier 1 and tier 2 levels of progression, to be explored and experienced.
Amazon Games and Smilegate RPG will continue to monitor but feel that Legion Raids, the definitive Lost Ark raiding experience, should be released after players have acquired enough materials to be confident and ready for the complicated challenges awaiting them.
Instead, what players will receive will be new classes, and new regions to explore, such as the South Vern continent. Between the various Chaos Dungeons, Guardian Raids, and the new Argos Raid, there should be enough endgame content to strive for, as it stands now.