A particular focus in League of Legends from Riot's point of view is the ability of players to react to rivals. This design key is one of the most important in their current philosophy, and has, in their eyes, given rise to some of the best champions.
Perhaps because of this, some interactions that have appeared in the game over the years are tremendously incomprehensible.
One of the most controversial and hated of these was the combination of the Zhonya's Hourglass active and Ryze's ultimate. From his last rework until Patch 8.3, the champion could become invulnerable when using Realm Warp, escaping opposition plays easily -- and taking his allies with him.
It was a a grossly unfair mechanic that seemed to have been eliminated forever.
However, a bug from Riot Games made it possible for this mechanic to return to League of Legends, albeit momentarily, following the 11.13 update.
A rapid hotfix was applied, before players could abuse it too much.
Fortunately, and although no-one knows how this bug returned to League of Legends, there is no more trace of it -- meaning it can't cause havok in our solo Q games.
Some League of Legends bugs have been in the game for years without Riot Games paying much attention to them. That has certainly been the case with Rumble, a champion seemingly with more than ten full pages of bugs.