Sea Monster Rarity: Common TYPE: Creature SUBTYPE: Serpent CMC: 6 Mana cost: USD: $0.09 EUR: 0.08 TIX: 0.06 EDHREC RANK: 28152 (6/6) This creature can't attack unless defending player controls an Island
While you wont always have Mantle of the Ancients in your graveyard, getting back a card like Thran Power Suit or Mithril Coat after an opponent spent resources to remove it feels like a strong move
The Set Booster always gives you one standard rare or mythic rare from the main set, so any rare or mythic rare in the wildcard slot is just extra goodness
Whenever you discard a card, if it has madness, untap Anje Falkenrath
Slamming Atraxa on most boards wins you the game outright, and you just draw a bunch of cards to make up for it if your opponent can answer it
However, While Wulfgar costs five mana and only doubles triggers based on its controller's creatures attacking, Isshin costs two less mana whilst also doubling triggers that may care about an opponent's creatures attacking, making Isshin simultaneously more flexible and more efficient of an option