One of League of Legends' most powerful abilities rendered testing servers unplayable for days thanks to a bug that made it almost infinitely spammable

A "gamebreaking" League of Legends bug ruined the game's testing server by allowing players to cast their most powerful abilities on never-ending loops.

League of Legends' Public Beta Environment (PBE) is the game's testing server, and it's currently filled with all of the new items that will be making their way to the game with the new season in January. One of those new items is Experimental Hexplate, which grants its owner some extra HP and some physical damage-related stats, as well as 30 Ability Haste (League of Legends' term for cooldown reduction) on their ultimate ability.

Last week, PBE players realised that due to a bug, if they purchased the item and then refunded it, they'd lose all of those stats, as expected - with the exception of the Ability Haste. As a result, they could purchase and un-purchase Experimental Hexplate over and over again, stacking their Haste until the stat's diminishing returns capped out.

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The result, according to YouTuber and prolific PBE tester Vandiril, was that every game was filled with characters constantly spamming their ultimates. In the video example below, Vandiril is playing Teemo, a character who's trap-based ultimate already has a very low cooldown, but they suggest that the real villain is Karthus. The lich-themed champion has perhaps one of the strongest ultimate abilities in the game, allowing him to strike every enemy with a powerful burst of damage no matter where on the map they are. There are only a few ways to reliably dodge a Karthus ultimate, and all of them are on a longer cooldown than these amped-up ults.

Since ~Wednesday on PBE we have a gamebreaking bug with Exp. Hexplate that makes everyone have 500 ability haste on their ultimates. Pretty much every game is 2 karthuses using his R every 20ish seconds.I know it's PBE, but with this bug it's impossible to playtest new season. pic.twitter.com/5CQCApUdB9November 25, 2023

Vandiril claims that "pretty much every game" features one copy of the champion on each team. Normally, that might not be a problem - Karthus's powerful ult is traditionally counterbalanced by his lack of defensive stats and a long cooldown - but Vandiril also says that at max cooldown, the spell is being cast "every 20ish seconds," all from the safety of Karthus' base.

Combined with other spammable ultimates, Vandiril says it was "impossible to playtest the new season." The issue first reared its head in the middle of last week, and by the time it had become common knowledge, many Riot developers were away on their Thanksgiving breaks. The item was reportedly fixed last night, but that only proved Vandiril's prediction that the testing server would be more or less completely unfit for purpose for around five days, hampering bugsquashing efforts ahead of the most disruptive time of the year for League of Legends.

Elsewhere, the new League of Legends world champion is sad because he can't get the "pretty" prize he really wants.

I'm GamesRadar's Managing Editor for news, shaping the news strategy across the team. I started my journalistic career while getting my degree in English Literature at the University of Warwick, where I also worked as Games Editor on the student newspaper, The Boar. Since then, I've run the news sections at PCGamesN and Kotaku UK, and also regularly contributed to PC Gamer. As you might be able to tell, PC is my platform of choice, so you can regularly find me playing League of Legends or Steam's latest indie hit.