Aphelios is League of Legends' marksman with one of the highest skill ceilings in the game but that didn't stop players from one-shotting entire teams mere days after release. As you can imagine, this was due to overtuned numbers, which have been reduced in a hotfix.
Aphelios has a massive kit and has to constantly micromanage the weapon rotation in order to be able to participate in fights at maximum efficiency. That maximum efficiency almost always requires having Infernum, the flamethrower, in one of the equipped slots but when that happens, Aphelios can just delete the enemy team.
We don't mean it figuratively either, as one-shot quadra kills and solo pentakills started popping up in League of Legends' subreddit, all of them using Moonlight Vigil (R) with flamethrower equipped. This all happened within the first week of the champion's release which obviously pointed at the champion being overpowered as such feats are usually not achieved until players get familiarised with new abilities.
Anyway, Riot Games decided to hit the common culprit behind these team wipes - Moonlight Vigil with Infernum equipped. First up, the damage has been decreased on the empowered attacks as it will scale less with bonus AD. More importantly, the AoE has been reduced from 500 units radius to 400.
With these changes, the Infernum-powered ultimate will still have the potential to turn the tide of a team fight but it will be harder to get one shot quadra kills. Proper skill shot placement will also be necessary in order to get as much overlap AoE damage as possible.
Furthermore, Aphelios' Q with Calibrum, the rifle, equipped will have lower attack damage scaling on the followup range-less attack. This change will limit his bullying potential and Jankos will probably not freak out as often . Who are we kidding - yes he will. He always does.