This is the cheap version that I made based on Kripp's heroic slitherspear mill rouge. I did it in 3 tries so I guess it's pretty good.
Mulligan: U want to keep back stab, saboteur, and cold light.
Strategy: DO NOT play a cold light by itself unless u have another one in ur hand or deck, if it's the last one play it with gang up, DO NOT USE VANISH unless u know that u'll die next turn. Just keep drawing cards and silence the nagas that are bigger 5/5 because they'll turn back to 1/1s. Eventually u'll mill the boss cuz he has tons of card draws and u have gang up to enlarge ur deck.
Replacements: 2* Preparation for a fan of knifes and refreshment Vendor, 2* annoy o tron for the bilefin tide hunters. And if u find the Cult apothecary not consistent enough or hard to use(it does require a bit of skill to know when to use it), u can switch both of them for 2* antique healbot.
Overall this boss is really hard, I think the only way to beat it with cheap decks is with mill rogue. Because blizzard made the AI smarter so summoning stone and animated armor won't work anymore. GOODLUCK!