The bug began when Scarra sold two units while his team was in combat with an opponent, which somehow resulted in his Varus, who had been on the field at the time, being transported to the bench, but continuing to fire at the enemy.
It’s not clear what would have happened if Varus had been the target on an enemy champion – if, for example, he would have been invulnerable to damage due to his position – because shortly after the bug occurred. Scarra’s team wiped out the last of the enemy units.
The bugs didn’t stop there, however. When combat ended, Scarra’s Elise had been dead, but the spiderlings she releases were still alive. After the board reset, one of those spiders had been placed on Scarra’s bench as though it were a champion unit.
Scarra decided to try selling the spider, but instead of being rewarded with some gold, he was instead charged 2 gold for the attempt – and the spider didn’t even disappear. Even worse, as he went into the next round, the spider had become an enemy spider that he wasn’t able to sell.
This meant that the spider seemed like it would be permanently taking up a spot on Scarra’s bench, space on which can be enormously valuable as the game progresses and players attempt to juggle levelling up their existing champions and keeping their options open by picking up new champions.
While Scarra was still trying to figure out what to do about this issue, it got worse – a couple of rounds later, yet another spiderling appeared on his bench.
Eventually, he decided to put in a spiderling as part of his team, which appeared to take up one of the five spaces he had. When the round started, however, the spider instead fought for the enemy team – although the game did at least auto-fill his squad with another champion from his bench.
That seemed like it would be the end of things, but the game had another twist in store. Not only did the spiderling reappear the following round, but Scarra was able to swap it out for another champion, resulting in him being able to field six champions despite only being level five.
Scarra eventually realized that this aspect of the bug only allowed him to increase his roster size by one more than his actual level – putting both spiderlings on the field didn’t let him add two additional champions beyond the number he should have had. He also couldn’t give any items to the spiders.
Exactly what circumstances caused this sequence of bugs to occur isn’t entirely clear, but given how big an impact it can have on the game, Riot will hopefully prioritize addressing it as soon as possible.