This trick allows Ryze to have an insane amount of mana regen, whether at the start or finish of a game
Despite being through a lot of reworks and modifications, the champion playstyle has always relied heavily on mana, which is something that hasn’t altered in Ryze. So, in order to properly play him, players must always pay attention to their mana consumption.
And recently, a Ryze ‘mana hack’ interaction was discovered and exploited throughout the League community. According to the video, players just need to walk in and out the river to gain a burst of mana.
This interaction is due to the recent mid-patch 12.5 buffs to Ryze, as his Passive maximum mana increased to 10% per 100 AP, along with the help of 2 runes: Celerity and Waterwalking. Essentially, his passive does not just convert his AP to his max mana, but also to his current mana.
Waterwalking will gain AP for the champion as you enter the river, and will remove the stat as you walk out of the zone. But the interesting part here is that, while his maximum mana will increase and decrease as you walk in and out the river, the current mana will stay the same.
As a result, Ryze may regenerate mana extraordinarily fast just by going in and out of the river on a constant basis. If you can apply this strategy, you may ensure that the mana is always at the threshold of sufficient usage at the start of the combat. Furthermore, this strategy is incredibly effective in the mid phase of the game, when Ryze’s item is still limited.
It is not clear whether this is an error or a feature of Ryze, hopefully, Riot Games will clear things out soon.