Hearthpwn

The whole and only point of the deck is to play up to 4 Yoggs(2 originally,2 from simulacrums). The deck does it quite effeciently,with 2 iceblocks,many freezes,card draw, I was often able to cycle through almost whole deck by turn 10. The deck is meant to be played at rank 5 for fun only, imagine winning by Yogg-Saron, Master of Fate eating your opponents board or rod of roasting,or Yogg-Saron, Hope's End changing sides by casting psychic scream/treachery and killing your opponent with fatigue. This deck is meant to bring joy to both you and your opponents,who are probably tired of boring meta decks. :) 

Mulligan is quite obvious,you can keep anything except freezes,yoggs and secrets or try to hard mulligan into Incanter's Flow

Possible replacements:

Laugh at me,but I put Raid the Sky Temple in the deck mainly to let my opponent know that I am not an apm/mozaki mage,which this deck is very similar to until late in the game. It helps raising spell count,but you can safely remove it(don't forget that Yogg is capped at 30 spells). Alternatively add Deck of Lunacy,though it will make drawing yoggs more difficult and transform Simulacrum.

You could find a place for Blizzard or Varden Dawngrasp by removing some of discover spells. This may make your early game harder and quest completion slower,but will let you buy more time later in the game. Puzzle Box of Yogg-Saron is a cool option too,however at 10 mana you are often already able to play Yoggs and surviving 4 Yoggs is not an easy task. xD