However, you can consider playing fewer than four copies of a card if: It gets worse in multiples (such as legendary creatures) It's only useful against certain matchups It's a win condition, and your control deck will have time to dig through the deck and find it You're stuck choosing between two cards which have equally strong, similar, but slightly different effects (you could play two of each) It's a slightly worse version of a card you have four copies of already, and you're including it because you want even more of that effect
9 Elemental - 528 Primal forces of nature, Elementals have been in Magic since the game's early days
Belle creates a complex decision point for your opponent in the early game
During my draw step, you target me with Funeral Charm's discard ability
Of course, one of those players could be you, giving you an erasy way to both get yourself ahead and curry the favour of everyone else at the table
Bring it in against an opponent who has multiple good targets