Back in July, Niantic introduced a new concept to Pokémon GO: Legendaries. Meant to be some of the hardest to catch, Legendary Pokémon are ultra-strong, appear only for a limited time and require players to form “raid groups” of up to 20 players to take them down.

It had a peculiar impact on the game. It by no means brought the game back to the crazy, just-after-launch days of seeing mobs of GO players wandering aimlessly everywhere you looked… but it definitely brought players out of the woodwork and brought them together. Successfully taking down a Legendary Pokémon meant organizing a sufficiently large group — which, in most cases, meant getting on your local Discord or Facebook group and setting a game plan.

As of later today, the first set of Legendary Pokémon (Articuno, Moltres, Zapdos and Lugia) are leaving — and, perhaps a bit surprisingly, three new ones are already prepped to take their place.

But there’s a bit of a twist this time: only one Legendary will appear in a given region at a time, rotating at the end of each month.

Here’s how it’ll look from August 31st to September 30th:

• Raikou (left, above) will be available in the Americas
• Entei (center) will be available in Europe/Asia
• Suicune (right) will be available in the Asia-Pacific

Come September 30th, they’ll rotate — and at the end of October, they’ll rotate one last time.

The last set of Legendaries was handled a bit differently: the same legendary was available worldwide, but only for a week at a time (until the last few days, at which point they were all briefly available simultaneously). It tapped a fear-of-missing-out that brought back a lot of players… but it also seemed to burn out a lot of them. Having to find a time to raid (or, more accurately, multiple times to raid, as the odds of catching a Legendary on your first try are actually quite low) every week was exhausting. By the last one’s arrival, many players I spoke to seemed tired of the grind.

So slowing the pacing a bit makes sense.

Meanwhile, Niantic says it’s rolling out a field test of the “EX Raid” system, or invite-only raids that you can only participate in if you’ve completed a raid at that location before. As someone who has seen some raids have upwards of 80 people while another raid at that same location failed to find enough players, this seems a bit overly complicated… but I guess we’ll have to wait and see. Niantic says the first EX Raid tests should hit around September 6th.