Because I Have Willed It

• WWizards of the Coast2017-06-13
  Official Ruling
  If an instant or sorcery spell has in its mana cost, choose the value for X first, then reduce the cost by . For example, Volcanic Geyser with X chosen as 4 costs to cast if this scheme is face up.
• WWizards of the Coast2017-06-13
  Official Ruling
  Abilities that reduce the cost of a spell apply after abilities that raise them. For example, Borrowed Malevolence with both modes chosen costs to cast if this scheme is face up.
• WWizards of the Coast2017-06-13
  Official Ruling
  If an opponent cast a spell during the opposing team’s turn and then left the game, that spell counts when determining whether the last ability of this scheme triggers.
• WWizards of the Coast2017-06-13
  Official Ruling
  For this scheme’s second ability to trigger, the players on the opposing team must have cast four spells total among them.
• WWizards of the Coast2017-06-13
  Official Ruling
  The second ability only checks that four or more spells were cast. It doesn’t matter if those spells are countered or fail to resolve for other reasons.
• WWizards of the Coast2017-06-13
  Official Ruling
  Effects that reduce the generic mana cost of a spell can’t reduce that spell’s colored mana requirements.
• WWizards of the Coast2017-06-13
  Official Ruling
  In a Supervillain Rumble game, the last ability of this scheme triggers at the beginning of each opponent’s end step if that player alone has cast four or more spells that turn.

Rulings via Scryfall