It's only been a few hours but this is just funny. Everyone says Ichman is bad so when I opened him as my first Legendary I had to build around him. This is what I came up with (thanks to also opening Vanndar). 

Early on you control the board with secrets and Bloodseeker and Petting Zoo.

Midgame you fight with your The Rat King and Mountain Bear hopefully discounted by Vanndar Stormpike early or a Carrion Studies.

Late you try and end with Wing Commander Ichman or Jewel of N'Zoth to build big boards. Dire Frenzy is there to assist reloading your deck with beasts for Ichman to hit.

Shadow Hunter Vol'jin is a real fun card against other "big" decks. Sometimes you can swap out a taunt or change one of your tokens out for a King Krush. Someone used that card on me which reminded me it existed. Very useful.

Mulligan: Vanndar of course, especially on coin. Studies to a lesser extent as well. Rat King can be great early control while secrets are great at delaying the opponent.  Bloodseeker too is strong against decks with a few weak minions like Wand Thief and Venomous Scorpid which can charge you up for big hits later.

Good luck, have fun and FOR THE H...uh Alliance I guess. Thanks Vanndar.