League of Legends players who squeezed in as many URF games as possible when the game mode was live recently will sort of get the chance to return to that experience again now that ARURF is being brought back. Riot Games announced this week that it's bringing back the randomized version of URF for another round of testing before it comes to live servers. Since it's been a while since ARURF has gone live, this means that it'll have all the new Rise of the Elements features that have been added like the updated Elemental Dragons.
Riot said in a post on the League boards that ARURF is now back in the game's test servers for players to preview it ahead of its actual release, so if you've got a PBE account, you're free to play it now. It'll have the updated dragons as well as the Dragon Soul feature that's been added to Summoner's Rift, and champions themselves will also be affected by an ARURF-specific list of balance changes like ARAM gets and similar to how the return of URF was handled.
For those who didn't play ARURF the last time it was around, the key difference between this mode and URF is that you don't get to pick your champion here. That's a deal-breaker for many players since they get stuck with random champions, but some people prefer that system since it means they won't have to play against the same overpowered champions every time.
This will also be the first round of ARURF that Aphelios is playable in, so if you've gotten the basics of the champion down since his release, you can hope to get him in the rotating game mode to unleash the powers of his five weapons much faster than normal.
As for the state of the original URF mode, it still doesn't seem likely that it's ever returning as a rotating game mode, but the verdict isn't in yet. Riot referenced its dev post from before that talked about the game mode and said the "results from the experiment aren't in yet."
"This is an experiment. We hope we've improved URF in meaningful ways, but we're planning on this to be a one time thing," Riot said when the original URF was brought back months ago. "We've been transparent in the past that URF seems to have a lot of detrimental effects on players in the long term—in particular, it makes people burn out and stop playing League all together. If this becomes the case again, even with the changes, we'll have no choice but to keep URF's return as a one-time special event."
ARURF is now on the PBE for testing and is expected to come to live servers soon.