No cooldown, no problem.
In League of Legends, bugs sometimes lead to game-breaking benefits.
The most recent champion to join the game, Vex has caused numerous bugs since its release in 2021. Recently, a Reddit user shared a clip of one of their Vex games where an exploit allowed an enemy Veigar to be destroyed in the hallway.
The clip begins with Vex and Veigar colliding with each other. Vex uses his Shadow Surge (R) to strike Tiny Master of Evil. To finish him off, the player reuses the spell to dash forward in Veigar's direction and finish him off.
Fortunately for Veigar, Evelynn comes to her aid and avenges him shortly after her death. However, when Gloomist respawns, the player notices that the cooldown for Shadow Surge has decreased and the ability is ready to be used again.
When Vex returns to the lane, he uses his ultimate ability a second time in a short time, once again to be very successful. Thanks to a well thought-out combination of skills, Veigar is sent to the fountain a second time. And Vex's Shadow Surge cooldown is reset once again.
As the player noted on Reddit, this bug led to a snowball, which caused Veigar and his team to lose the game.
Many players point out that this bug has been in League for months and as we can see it is still not fixed. They point out that duplicating is simple, and they hope Riot fixes this as quickly as possible. In the meantime, you might consider banning Vex in your games.