Hosted by Leaguepedia, the LoL Fantasy League allows you to create your own Fantasy Roster that follows the NA and EU LCS scene.

You can register here: http://www.leaguepediafantasy.com/

Their website is kinda buggy, and honestly poorly done but it's a cool concept.
You may not be able to create a Roster until the end of the weekend when the EU LCS ends since they lock in your weekly roster at the beginning of the NA LCS (Thursdays).

You start with a $100 limit and you can buy members of all of the LCS teams from NA and EU based on how they played the following week. Their scoring formula is listed here: http://www.leaguepediafantasy.com/lol-fantasy-scoring-formula/. Once the week ends with games, you can choose new players for your roster for the next week, that either gain or lose their value according to their performance the follow week, to obtain the maximum points possible.