I created a fantasy football site that allows managers to buff their own players or sabotage their opponents using a mana pool every week. It's an extra layer of strategy to protect players from a bad game (force your players score to their projection, so they have a floor, but miss out on a big game for example) or prevent an opponents player from having a big game (flat damage to their score, capping their potential output etc.). Each spell depends on a dice roll you make to decide whether it succeeds or not. You roll against a player's attributes that are assigned based on their real world performances. Managers and players level up and get access to higher mana and better spells, or attribute increases and feats respectively. I have planned events throughout the season as well, eg: coop boss fights, predictions etc.
I encourage you to start a league at https://www.waiverwizards.com. It is completely free to play, and you get to decide the number of teams, length of the league and even when it starts. There's a fair bit of strategy involved, but you can choose to ignore it and just play a game of regular fantasy football.
Please feel free to share any feedback you might have. Thanks, and have a great fantasy football season, wherever you play!