Regarding the Aurelion Sol Remake

TL;DR: We’ve identified the cause of this bug, and it’s unique to Aurelion Sol. We’ll be implementing a fix on 6.18 (the Worlds patch). Read on for all the details.

Yesterday during the NA LCS Semifinals between CLG and TSM, a game had to be remade due to a player seeing a Aurelion Sol's passive missile in the wrong place.

Aurelion Sol's passive has the longest lasting missiles in League's history by quite a large margin, and they exposed a set of technical limitations we had never hit before with missiles. Most pertinent: this is the first time a missile is defining its motion around a unit that does not share its visibility. Previous missiles that moved based on another unit, like Ahri's Fox-Fire, share visibility with their owner - you only see the missile if you see the unit as well.

In order to cope with this new problem, we put in some handling where the client is sent positional information about Aurelion Sol if one of his missiles is in vision but he himself is not. This allows the missiles to represent their movement without having to fully reveal the champion. However, there is a small time gap between the client gaining visibility of the missile and when it receives this positional information, and that gap is what ultimately led to Sunday's remake.

A brief timeline, based on Twitch's VOD:

• 10:29 game time (43:38 video) - Aurelion Sol's passive spotted over wall by ward at blue buff
• 10:31 game time - Aurelion Sol and his passive fully leave TSM's vision
• Aurelion Sol remains out of TSM's vision until:
• 11:06 game time - Aurelion Sol's passive spotted in mid lane by Rek'Sai

For a few frames at game time 11:06, TSM Bjergsen's client displayed one of Aurelion Sol's passive missiles at the position it would have been if Aurelion was at his last known position - game time 10:31. It had received the information saying that the missile should be made visible, but had not yet received an update on where the champion was, so it showed the missile relative to his last known position.

This Aurelion Sol defect has been present since he shipped. We had some code in place to mitigate effects of this nature for him, but they were clearly not enough. In the affected game, the circumstances were such that a player's decision making was negatively affected, and lead to a remake. We are fixing the issue by preventing the client from showing these missiles in the absence of accurate positional information. This fix will be a part of the 6.18 patch cycle, which is the patch Worlds will be played on.

Regards, ~Riot Penrif