Dropping one damage counter on every opposing character can have huge ramifications, especially with so many viable combinations of cards that affect already damaged characters
Rules are great, arent they
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While it can be dealt with cleanly by a Swords to Plowshares, assuming you managed to hit a creature or planeswalker of theirs, they would have paid three cards (Swords, discarded card and creature/planeswalker) for your one (Entomb/Faithless Looting and reanimation spell offset by drawing a card)
Look for cards without bends, scratches, or visible wear
If you discard a card with madness, it goes to exile rather than your graveyard