In the current state, players are required to own sixteen champions before they can start testing the brutal waters of the League of Legends ranked ladder.
The threshold was placed on purpose by the developer to ensure that a player has enough champions to either fill multiple roles or not be completely banned out during the drafting phase. With the continuous evolution of the game, those rules need to be slightly adjusted.
According to communication specialist Riot Draggles, players will soon be required to own twenty champions before they can queue up for League of Legends ranked games. This change is based on two factors.
you'll need 20 champs (up from 16) to play ranked when we implement 10 bans in regular play – oh look, there's a double IP weekend on now!
— Ben Forbes (@draggles) April 21, 2017
Firstly, the developer is about to increase the number of bans from six to ten during the drafting phase to take into account the larger roster of champions than before. Secondly, a number of champions have seen their prices reduced in recent years, making it more easier for players to increase their rosters.
The new League of Legends ranked requirement is being introduced to make sure players cannot be completely banned out, and that they must have a bit more of game-time before venturing into ranked games.
There is no confirmation on when the requirements will be raised, but will arrive when the bans are increased. Since the developer has not mentioned so, it seems unlikely that it will be part of the mid-season update, scheduled to release next month. Expect the champion-limit to arrive sometime after.
The upcoming League of Legends mid-season update will bring massive changes to a number of tank champions, raising their learning curve and giving them more to do in team fights. In addition, it will add Support Quests to make the role more appealing for the community. Finally, there is the new Rift Herald that will fight under a team’s banner.