Heroic Moding:
Grim Guzzler (1st):
Beat this first try with a custom rogue deck that had 2x betrayal, 2x sap, 2x backstab, 2x gang up, and then I loaded the rest of my deck with every huge 8+ cost legendary I had. I think it was first turn I got a 8/8 clockwork and he got 2 4/4s - i gang up'd it, and drew nothing but 8/8s and then betrayal'd his 4/4s into each other for board control.
Arena (2nd):
Beat this after 4 attempts with a custom Shaman deck. All control cards (lightning storm, hex, bolt, crackle, 2x windfury, 2x ancestral call (the ressurect one) 2x reincarnate, 2x Ancestors Call (big play here) and only 2 creatures- Sneeds and Kelthuzad
I mulliganed my hands until I got Far Sight / Hex / Ancestors Call / Sneed or Kel in my opening hand. I originally anticpated the Millhouse turn 1 drop, but instead he went Pagle + Lorewalker cho. I shifted gears from trying to pull an early Kel + Sneed infinite combo into a slow roll board control race. So he had 2 0/4s and 2 1/1s, I hexed his next Sylvannas and then drew into another hex for his Mogor the Ogre. He had a full board of 0/1s, 3 1/1s and a 2 0/4s - so I slow played it til I played Spirit Wolves to eat the hexes I played (and he copied from Cho) then laid down Sneeds and reincarn + kill+resummon combo and filled my board up with more legendaries than he could deal with. He couldn't play spells because his hand was full and board was full, I got down to 11 hp from him smacking me with 1/1s before I lightning storm cleared then dropped Kel and just traded + smashed face.
I got down to 4 HP - he burned Geddon when he had a full hand, and he drew Flame Leviathian which dropped me to 2. Pretty fun heroic.
Emp (3rd):
Beat this after 3 attempts as well with a Priest deck. Idea was simple: Get a Stoneskin Gargoyle out, give him double health x2, then inner fire. I dropped Stoneskin turn 4 with a power word shield, he equipped Deaths Bite (2 turn clock basically). I drew into both double health cards and had inner fire, so I two-shot him and lived with 1 HP.