Millennium Sword

The structure

The number of boss sets can vary season to season. Currently, there are 2 Sword Trial sets and 2 Hero's Realm sets, each with 3 qualifying phases — this configuration can change in future seasons. A phase is a time-bounded window scheduled ahead of time — it opens, stays open for a while, then closes, and once it's closed it's gone for the rest of that season. Every phase runs on two separate leaderboards at once: Normal and Challenge Mode. Qualifying on one doesn't require or exclude the other — they're tracked completely independently, and either one counts toward this achievement.

How to qualify

You don't need every phase — just one qualifying phase per set, on either leaderboard. Whichever phase you happen to qualify in, and whichever leaderboard you qualify on, both count exactly the same toward this achievement. There's no bonus for qualifying in more phases of a set you've already covered, and no penalty for qualifying on Challenge Mode instead of Normal, or the other way around — the moment any one phase of a set has a qualification logged against it, that entire set counts as done. The achievement itself unlocks the moment every set for the season is done, in whatever mix of phases and leaderboards actually happened.

A worked example

Here's one real path to earning it — notice the leaderboard changes set to set, and no set needed more than one phase:

Every set qualified — the leaderboard and phase were different every time, and that's completely fine. Nothing else about this player's other phases or leaderboards matters.

Seasons

The achievement runs fresh every season, with new boss sets, new names, and new qualifying windows — a phase that's closed for this season doesn't carry over or come back. Your tracker page lets you switch between seasons to see current and past progress separately, and each season's own sets are tracked completely independently of any other season's.