Because I Have Willed It is a common Ongoing Scheme card from Archenemy: Nicol Bolas Schemes (OE01), collector number 1★. Current market price: $2.98, TCGplayer market prices via Scryfall.
(An ongoing scheme remains face up until it's abandoned.) Spells you cast cost {1} less to cast. At the beginning of your opponents' end step, if they cast four or more spells this turn, abandon this scheme.