Edit: This has reportedly be fixed.
According to reports that started yesterday when Season 2 went live, some players were claiming to get the Midnight Season 2: Catalyst Unbound early. Amongst other rumours that turned out to be false (e.g. Superbloom), this one didn't seem to be consistent at first, as there were players with their 2-set that did not get the achievement. After further investigation by players, it seems like the result is that this is limited to the Hunter Class and is clearly a bug.
We are not reporting on how exactly this happens, due to the uncertainty of whether or not this is actionable. If you find out how to do this, use it at your own risk of account actions.
Why does this matter? The Midnight Season 2: Catalyst Unbound allows players to accumulate more Catalyst Charges from various Season 2 activities. This is introduced so that players feel incentivized to use their Catalyst charges to get any item level of 4-set, and then can farm more to upgrade it later. However, this achievement being available early, when a player only has 2-set, means that this turns into a method of Tier Acquisition, rather than just Item Level upgrades. This complicates things as one class out of the 13 in WoW only needs to get their 2-set, and then can farm more Catalyst Charges from activities to more easily acquire their 4-set. This is something that guilds will account for when doing Loot Council during raids.
