Flunk

Kill spells that scale with hand size usually punish the opponent for being flooded with cards; this one inverts the axis and punishes them for spending. At seven cards in hand the effect is nothing, a wasted instant. At an empty hand it is a clean -7/-7, enough to erase almost anything the game will present. The design ties removal quality directly to the tempo state of the board: it wants the moment after a spent turn, the empty-handed alpha strike, the topdeck war where both players are hellbent. That makes it a specialist. Against a control opponent hoarding answers it does close to nothing, and against a fresh hand it is dead weight, but against the aggressive or all-in decks that dump their grip to close a game, it grows into a two-mana catch-all right when the opponent is most committed. The instant speed matters here as much as the sliding scale: you get to wait for the attack, count the empty hand across the table, and let the size resolve itself before you commit. It is a piece of removal whose power is decided entirely by information the caster does not fully control, which is a rare and pointed thing for a black kill spell to be built around.