Sewer PlagueHow it works & interactions with other cards

What It Does

When you cast Sewer Plague, you target a creature an opponent controls. That creature immediately receives a perpetual -2/-2 debuff and gains a new triggered ability that triggers at the beginning of every upkeep, further reducing its power and toughness by -1/-1 perpetually each time it fires.

The Power of Perpetual

The key feature of this card is the 'perpetual' keyword. Unlike standard effects that end at the turn's conclusion or when a permanent leaves the battlefield, perpetual changes follow the card into the graveyard, hand, or library. Even if the creature is resurrected or returned to its owner's hand, it retains the stat reductions and the upkeep-trigger ability.

Resolution Step-by-Step

First, you choose a legal target controlled by an opponent and pay the mana cost. Upon resolution, the creature is modified instantly. At the start of the next player's upkeep (and every upkeep thereafter), the new ability triggers and goes on the stack. When that trigger resolves, the creature's stats drop by another -1/-1 permanently.

When to Play It

Sewer Plague is best used on creatures with high toughness that you cannot kill immediately, or on utility creatures that an opponent might try to recur from the graveyard. Because the effect persists, it effectively ruins the card for the remainder of the match.

Interaction examples

Permanent Decay vs. Sacrifice

Deadly Dispute

If you cast Sewer Plague on an opponent's creature and they respond by casting Deadly Dispute to sacrifice that creature, Sewer Plague will fizzle because its target is no longer legal. However, if Sewer Plague resolves first, the creature is perpetually shrunk. Even if they later sacrifice it to Deadly Dispute, should they return that creature card from the graveyard to the battlefield later, it will still have the -2/-2 and the shrinking ability.

Exile Trumps Perpetual

Deadly Rollick

If you apply Sewer Plague to a creature and then later cast Deadly Rollick to exile it, the perpetual effects remain on the card in the exile zone. While the card is unlikely to return from exile, if an effect were to put that card back into play or into a hand, it would still bear the scars of the plague.