Dominion was first introduced in September 2011 as a permanent 5v5 game mode in League of Legends. The game mode was a fast-paced 25 minute alternative to the then 40-minute long Summoner Rift matches. Over the years Dominion gathered a few fans but due to a falling player base, Riot Games eventually decided to retire the game mode in February 2016. Dominion, at its time, provided a fresh new take on 5v5s with the brand new Crystal Scar map and capture and hold style gameplay. Many die-hard fans of the game mode still long for Dominion’s return in some form, even as a rotating game mode.
Crystal Scar was a map featuring five capture points in a star shape around it and jungle paths between the points. The objective was to capture the five points on the map successfully, draining 500 enemy nexus points to win.
Riot had originally intended for Dominion to be a permanent game mode, even adding a draft queue and confirming that a ranked queue was in the works. However, after the game mode’s release, it became clear that it wasn’t going to be as popular as Summoner’s Rift. Player numbers fell drastically as most just came for a one-off ‘fun and fast’ game between their Summoner Rift matches. Champion balance changes only catered to Summoner’s Rift, leading to no real solid 'meta' in Dominion, further making it an anything-goes game mode. Dominion’s champion select also had a bug that did not give players leave penalty for dodging champion select, something which Riot took a long time to fix. Although Dominion had a cult following which later started a competitive scene for the mode, it wasn’t enough to sustain the mode causing very long queue times. Lower-level League of Legends accounts also encountered several bots in games. These things lowered the overall playing experience on Crystal Scar. In its last days, Crystal Scar became a playground for community-driven modes like 'hide and seek'. In the post announcing the game mode’s retirement, Riot confirmed said
“Fewer than 0.5% of players actively play Dominion and we’re aware some number of even that small population is still bots. We haven’t been supporting Dominion, and we’ve trapped ourselves in a vicious cycle where the queue isn’t large enough to warrant major attention, but falls prey to bugs and periods of imbalance from the introduction of new champs and items (which then drives down the size of the queue, and so on).”
While Dominion has not returned to League of Legends, two newer modes have used the Crystal Scar setting. Riot added ‘Definitely Not Dominion' as a featured game mode and introduced it to the game on May 27, 2016. Definitely Not Dominion was the same capture and hold style game but with three capture points instead of five.
Another mode called Ascension was a recurring temporary game mode originally made for the Shurima event available in September 2014. It used the Crystal Scar map and added a new twist to the mode with a boss fight. However, since its last appearance in November 2017, Ascension has not been seen in the rotating game mode pool. In a Reddit post in December 2020, Riot Reinboom said
“Ascension is unlikely to come back in the form you're familiar with. If it's coming back, it'll come back on a different map. Currently, we've actually considered modifying the Nexus Blitz map for it (given how rounded the Nexus Blitz map is).
The Crystal Scar is dead. Like so dead. Like omg dead.”
So, it is highly improbable that Riot will ever bring Dominion or even Ascension back on the Crystal Scar map. If it does, it will likely be a rotating game mode as Riot Xenogenic said in an Ask Riot post that the developer is looking to bring back more new and old game modes.