Custom skins

yah i as long as no one else can see them they are legal

also don't use "MKJogo" just a heads up because this is a third party program, instead for custom skins just use leaguecraft

This is the reply Riot Support gave long time ago:

While we don’t strictly condemn the use of third-party modifications, these programs can be dangerous and worthy of suspension where they violate our Terms of Use. I can’t tell you whether a particular third-party modification is against our Terms of Use or not, but you can follow these general guidelines:

We identify and suspend accounts for using third-party programs intended to offer a competitive advantage by affecting gameplay in any way We cannot control what a third-party developer makes or changes, so a program that was once acceptable may have versions which violate the Terms of Use Some third-party developers may not have your best interests in mind, so please be aware that these types of files can contain keyloggers, viruses, and malware. Third-party modifications may affect your game in unexpected ways, so if you’re having technical issues, try uninstalling these programs before doing anything else. In general, if you find a third-party modification suspicious, it’s best to avoid using it. I hope this clears things up a bit, but if you have any other questions, please let me know.

Also, if you need more information, please access this link: http://boards.eune.leagueoflegends.com/en/c/announcements-en/bm6LA7EG-reminder-third-party-applications

In there you will find the following sentence:

"No software should interfere directly with the in-game player experience between when you press “Play” and the end of game screen."