3UU
Legendary Octopus Rogue
When Prognoctopus enters the battlefield choose an opponent and an outcome (win/lose/tie). Reveal the top card of that player's library, as well as your own. If the card revealed by the opponent has a lower caster cost, and you chose win, draw 8 cards. If the card has a higher casting cost and you chose lose, gain 8 life. If both cards are equal and you choose tie, destroy 8 target non-octopus creatures. If you did not choose correctly, sacrifice prognoctopus and that opponent creates 8 0/1 tasty calamari treats with sacrifice this creature: gain 8 life.
Actually, since this card is unblockable, I can see running it WITH Yuriko. If the enemy has a big nasty out, you get to remove it, otherwise you jut use Etrata to Ninjutsu Yuriko in. Basically, use Etrata as a Ninjutsu enabler who also happens to have a situationally good removal attached to it, without caring too much about the alt wincon.
Or, to borrow my favorite kamigawa limited trick - give her first strike, deal damage, etrata trigger, ninjitsu. Do 3 damage, exile a critter, bounce her for her next mission and get your ninjitsu "double strike" damage and trigger...
1
3UU
Legendary Octopus Rogue
When Prognoctopus enters the battlefield choose an opponent and an outcome (win/lose/tie). Reveal the top card of that player's library, as well as your own. If the card revealed by the opponent has a lower caster cost, and you chose win, draw 8 cards. If the card has a higher casting cost and you chose lose, gain 8 life. If both cards are equal and you choose tie, destroy 8 target non-octopus creatures. If you did not choose correctly, sacrifice prognoctopus and that opponent creates 8 0/1 tasty calamari treats with sacrifice this creature: gain 8 life.
0/8
1
Or, to borrow my favorite kamigawa limited trick - give her first strike, deal damage, etrata trigger, ninjitsu. Do 3 damage, exile a critter, bounce her for her next mission and get your ninjitsu "double strike" damage and trigger...