The Unagi of Kyoshi Island

The draw trigger does the real work here, and it punishes a specific, common breach of parity: the opponent who draws a second card in a turn. Nearly every draw engine, every extra-card spell, every cantrip past the natural draw step trips it, and each time it does, you draw two. That reframes card advantage as a shared resource the opponent cannot exploit without funding your hand instead of theirs, and it rewards you for doing nothing but keeping the body on the table and letting them play their game. Flash and the Waterbend-costed Ward keep that presentation cheap to hold and expensive to remove: you can leave the 5/5 up as a surprise blocker or drop it once a turn is winding down to dodge a sorcery-speed answer, and anyone pointing a spell at it owes first. The wrinkle in that Ward is how the tax gets paid. Because the Waterbend clause lets each artifact and creature the caster controls tap in for on top of normal mana, a wide, board-heavy opponent covers it without breaking stride, while a stripped-down one scraping for lands finds it a real wall. So the protection is at its softest against the developed decks that most want to kill the thing, and at its hardest against the ones already on the back foot. A serpent that flashes in, guards itself against the impoverished, and siphons cards off every overeager turn the opponent takes.