When it's summoned onto the battlefield, the one who summoned it can choose a player and True-Name Nemesis has protection from that chosen player
Sure, you only get one of the three cards into your hand, but the others going into your graveyard is easily exploitable
This legendary human cleric can be a great payoff for a discard deck or simply a good sideboard card in a white-heavy meta
While you can trade Underground Sea for Watery Grave and hardly notice the difference, you are going to feel the difference when you top deck a Magus of the Wheel rather than a Wheel of Fortune when you really need to refill your hand, and you'll feel it a lot
A cards name is always considered to be the English version of its name, regardless of printed language
A word to the wise, though: eventually, your opponents will kill this