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

gamesradar.com:

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.

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