Echo Fox Academy members Tristan "Cake" Côté-Lalumière, Mingyi "Spica" Lu and presumably Joshua "Mabrey" Alan Mabrey intentionally banned main champions for two of their teammates in a ranked League of Legends match, sparking controversy.
Griefing and toxicity are highly forbidden in League of Legends, but it is currently unclear if all forms of it are bannable. Several fans have pointed out that unless Cake, Spica and presumably Mabrey taunted, insulted or otherwise griefed their teammates in written form, they could get away with it unscathed.
When the trio were matched with Tyler1 and Willie fkn P in their team, both of which are known for playing their niche champions, they opted to grief their teammates by denying them a chance to play those champions.
Tyler1's fame, and sometimes infamy, in League of Legends made sure that everyone knows his main champion is Draven, although he tends to play other marksmen depending on the current meta. For the moment it is Quinn, a champion that is dominating several roles right now.
Willie fkn P is known in higher ranks as a one trick pony who relies on his Udyr to climb the ranks. Needless to say, EF Academy trio promptly banned all three champions so their teammates couldn't play them, after which Cake took to Twitter post a troll tweet claiming they were "promoting one trick ponies to extend their champion pool to make sure they are eligible for scouting grounds".
Considering Tyler1 actually has experience with more than one marksman, and that neither him nor Willie ever expressed they wanted to play professionally, it was clear that Cake was trolling. Realising that the trolling could have consequences, he promptly deleted the tweet, but it was already too late as screenshotting things on the internet is rather easy. For example, here is a picture proving that the trio banned Tyler1 and Willie's preferred champions.
PainlessDeath22 is one of Cake's alternate nicknames in the game, while there is currently a debate whether Godspica is actually Spica or Dardoch, but evidence so far points to the former. Bear in mind that TEAMLUKEEE hasn't been clearly identified yet, although suspicions so far are that it's Mabrey, as he was duo queueing with Cake, on two different accounts.
In response to the controversy, Cake posted sort of an explanation on Twitter, stating he tried his best to win the game and that it shouldn't be acceptable that people are able to grief based on what champions were banned. It really doesn't seem like he tried his best though, as 3/12/8 score on Swain in bot lane seems rather weak. Cake is also known as a toxic player and he broke five out of nine Summoner's Code guidelines during this incident, which was pointed out by a careful observer.
It's also not true that Tyler1 griefed, as he had the best score and quite frankly looked like the best performing player on the team, even though he was forced to pick Nunu, an off-meta champion he doesn't have much experience with. You can watch a replay of the game and judge for yourself.
There is also an ongoing discussion on reddit at the moment, in a thread that had to be reposted after moderators dubiously removed the first one. It remains to be seen whether these players will be punished for griefing by either Riot Games or Echo Fox organisation, as professional players are influencers in the community, and griefing is anything but a good example.