The deck speaks for itself, but I'll add a few notes.

Also, I think this deck works really well in both BO1 & BO3.

Objective

You keep the board clean and simply survive until you can play Kiora Bests the Sea God.

Kiora Bests the Sea God is such a powerful card with so much value that this by itself is enough to win you the game.

Card Purpose

• Dovin's Veto is mostly there to protect your Kiora Bests the Sea God.
  But there are a lot of powerful non creature spells these days that can get countered, so it's definitely right to main deck 4 copies of this card.

• Teferi, Time Raveler is mainly used to stop the opponent from countering and that little bit of extra card draw is also very useful.
  Without Teferi, Time Raveler you're probably not going to have enough card draw. It's a crucial and versatile card. Keep this in mind if you want to replace it.
  
  
• Legion's End is obviously to deal with aggro, because there is a lot of very efficiënt and strong aggro right now.
  Replace it with Despark or Thought Erasure if you're playing against control.
  
  

Tips

• This deck is heavily teched against aggro because there is a lot out there right now. And your kraken is enough to beat control anyway. But just in case you're having trouble against control, there are extra answers in your sideboard.
  
  
• In your oppening hand you keep all the low cost cards plus Murderous Rider and Teferi, Time Raveler.
  
  
• I usually keep Murderous Rider around for planeswalkers because this is really the only answer you have for planeswalkers if you don't count counter spells and Despark.
  Against aggro you'll want to use it as a body to block creatures of course.
  
  
• If you're playing against control, then keep at least one Dovin's Veto around to protect your Kiora Bests the Sea God.
  
  

Sideboard

• Mortify
  For when you really need to get rid of that one annoying enchantment. It's also extra removal.
  
  
• Thought Erasure and Despark are more useful when you're playing against control. You can replace something like Legion's End and Tyrant's Scorn for these cards.
  
  
• Ashiok, Nightmare Muse
  Ashiok is just extra value and it's annoying for your opponent to deal with so it baits removal and recources. 
  
  
• Thought Distortion
  One copy of this card is great against heavy control decks that manage to destroy or exile your Kiora Bests the Sea God somehow. Sometimes having a few counter spells isn't enought to protect your kraken.

Replacements

• You could potentionally put Cry of the Carnarium in your sideboard if you're still struggeling against aggro.
  
  
• Agonizing Remorse could be added for the opposite reason, if you're constantly playing against heavy control.
  
  
• Ashiok, Nightmare Muse in the sideboard could be replaced with Liliana, Dreadhorde General.

I love Kiora Bests the Sea God, I think it's such a cool card. I hope you have fun playing with this deck.

By the way, can you tell I like consistency? That's why I play 4 of everything :)

Cheers.