About 80% win rate. From 10 to 5 in 5 hours.
Always keep Backstab (it does not need to be discussed 😊 ). Prince Keleseth because the sooner you buff your deck the better. Fire Fly is also a good keep as it is your the only 1 mana drop. Hench-Clan Thug is a really good 3 mana drop while you got your weapon equipped.
With Coin SI:7 Agent to kill enemy’s 1 and 2 mana drops. Elven Minstrel to draw early.
Perfect opening hand is with Fire Fly, Prince Keleseth and Shadowstep.
You don’t want them to dominate the early game so always keep Backstab, Fire Fly, Prince Keleseth, Fan of Knives and sometimes it is good to keep Saronite Chain Gang to protect yourselves from enemies rushing in your face.
vs Hunters !ALWAYS KEEP! Chief Inspector, because there is nothing more savage than playing it when the enemy has 3 or more secrets on the table 😉 .
You want to play really aggressively in early to leave the opponent on low HP, before he draws his defence and then finish him with Leeroy Jenkins and Cold Blood.
Keep Prince Keleseth, Fire Fly, Hench-Clan Thug, Cold Blood to dominate early.
It is good to keep Elven Minstrel when you got Backstab or Coin to strengthen your hand.
vs Warlock: If you got good early in opening hand you can also keep Vilespine Slayer to prevent him from taking advantage playing Mountain Giant early.
Replacements and Cores
Prince Keleseth is an absolute core in this deck as it buffs pretty well with Shadowstep and Spirit of the Shark and gives a lot of value.
The archetype of the deck describes another core: Spirit of the Shark which works pretty well with other cards ( Fungalmancer buff +4/+4 is pretty awesome :) ).
I would rather not advise you to replace Edwin VanCleef as it is a real problem for your opponent when you play it with Spirit of the Shark.
Gral, the Shark is not a necessity in this deck as it can be silenced, polymorphed, hexed or sapped and you will lose 1 or 2 minions. The better choice is Sonya Shadowdancer as it gives a lot of value ( Saronite Chain Gang 1/1 summons the 2/3 because of the latest 'nerf' ).
Leeroy Jenkins can possibly be replaced with Reckless Rocketeer but have in mind you would not be able to use the combo charge + Cold Blood + Shadowstep + charge as it will cost you 11 mana instead of 8 when you play Leeroy Jenkins
If you don't face many hunters you can replace Chief Inspector with any card that would work with the deck archetype.
Zilliax is not a core but it helps you survive as it is your the only heal. Works really well with Cold Blood. But as survival, you can replace it with Bonemare.
Instead of Seaforium Bomber you can try Gurubashi Hypemon for more value :)
kiwiinbacon has made a wonderful video showing how the deck works and how he wins some games with it. I am encouraging you guys to check his YT channel :)
Also user named Khristophesaurus Dinosaurus made a YT video playing this deck :)