Chains of Mephistopheles
The most famous card in Magic that almost nobody has played a real game with. The original wording was a mess of templating from a pre-Sixth-Edition rules world; the modern Oracle text cleans it up into the sharpest expression of a single design idea: replace the draw, and make the replacement bite. Every draw past the first in a player's own draw step (draws taken on an opponent's turn get no exemption at all) becomes a forced loss of resources. The replacement is not a choice: if you have a card in hand, you discard one and then draw, a rummage that costs you a card from hand even as it shows you something new; only when your hand is empty do you mill the top of your library and replace nothing. Either way the engine grinds your resources down rather than refilling them, and the tax cannot be played around by drawing fewer cards, because the cantrip you cast to dig is the exact action the enchantment punishes. The design is structurally hostile to the entire category of blue card advantage in a way few two-mana enchantments since have matched: not a counterspell, not a discard spell, but a permanent that turns the act of drawing into a slow bleed. Its reserved-list status and Legends-only printing have kept it a curio, but the design itself remains a reference point whenever R&D talks about taxing card draw without banning it.
