Thermal Flux

A cantrip built almost entirely to interact with a single mechanic, and that mechanic is the rarest one in the game: snow. The modal choice toggles a permanent's snow-ness in either direction, which reads like a designer's in-joke until you remember that snow is a property other cards check for. Turning a permanent snow can switch on a snow-matters payoff for a turn; stripping the snow type off something can shut off an opponent's snow-dependent ability or downgrade their snow mana source. The delayed draw, a triggered ability that fires at the next turn's upkeep rather than on resolution, is the only reason the card was ever castable: it makes the toggle free in the long run, so even when neither mode matters you have spent one mana to cycle. That construction (a near-blank effect stapled to a deferred draw) is a recurring shape for cards whose primary text is too situational to earn a slot on its own. The breadth hides inside the narrow word. Snow is a supertype, not a color or a mana value, so the toggle reaches permanents nothing else can categorize the same way, and any card keyed off snow status inherits this as an enabler or a disruptor without a line of errata. It is a hinge for a mechanic that barely exists, sold at the price of a cantrip so the niche use never costs you a card.