Curse of the Pierced Heart

A clock you cannot trade with. Most aggressive red cards put the damage on a body or a spell, which gives the opponent something to block, kill, or counter; this puts it on the player and then forgets about them. There is no creature to remove, no spell to redirect, no way to gain the tempo back short of enchantment removal. The cost is that it does nothing else: one point per turn, never more, with the only flexibility being the choice to redirect that point onto a planeswalker the cursed player controls. That redirect clause is the quiet part of the design, turning a steady life-total drain into a slow planeswalker assassin when the moment calls for it. It asks an aggressive deck to count the turns the game will last and decide whether a guaranteed point each upkeep beats a card that might do more but can also be answered. Of the Curse cycle, it is the purest version of the idea: an Aura that enchants a person rather than a permanent, ticking away on the margins while the creatures do the loud, vulnerable work.