Hearthpwn

All credit goes to Colonel_zx.

This deck is pretty simple, you just mulligan for Knife Juggler Radiant Elemental Test Subject Embalming Ritual Topsy Turvy

If you get any of those cards, keep them. The rest of the cards in the deck are just to keep you alive until you get the combo off. How it works is you need at least 5 mana, then you drop knife juggler, radiant elemental, test subject, then you play embalming ritual and topsy turvy. You go infinite by playing those two cards over and over on the test subject. It takes a while, around 15 mins or so, but since turns are unlimited time, it works 100%. 

Pretty sure it would work on other heroic bosses too, but it definitely works on Galakrond.

Topsy Turvy x 2
Embalming Ritual x 2
Flash Heal x 2
Power Word: Glory x 2
Power Word: Shield x 2
Test Subject x 2
Dead Ringer x 2
Knife Juggler x 2
Penance x 2
Radiant Elemental x 2
Shadow Word: Death x 2
Greater Healing Potion x 2
Mass Dispel x 2
Mass Hysteria x 2
Lightbomb x 2

Good luck!

Proof

https://hsreplay.net/replay/HiX9bvZTRZ6prXoHPEyb38