I fooled around with a few decks to beat Heroic Sapphiron with in Hearthstone.
I beat the Normal Mode version of Sapphiron with a simple Warrior deck. The Heroic challenge is obviously much more difficult because none of your minions will last longer than one turn.
I experimented with Warrior at first to beat the Heroic version, but found I just didn’t have the cards for it.
To beat Sapphiron on Heroic you need the perfect control Warrior deck with Shield Slams, Execute, Gorehowls, and Brawls. I just don’t have all those cards and they’re too expensive to craft.
I do have almost all the Mage cards though!
Here’s the Mage deck I used to pummel Heroic Sapphiron into the dust.
Arcane Explosion x2
Frost Nova x2
Ice Barrier x2
Ice Block x2
Mirror Entity x2
Cone of Cold x2
The strategy is very similar to a freeze Mage deck. Stall the opponent out until they’ve run out of stuff.
With the perfect draw it’ll work to prevent Sapphiron from killing you.
Counterspell is very useful for getting rid of Sapphiron’s Pure Cold spell. Mirror Entity will often soak up a Frostbolt if it doesn’t let you trade for a creature.
But how do you kill Sapphiron?
The first bit of damage should come from your hero power. Use it on her whenever you can afford to.
The second bit comes from any left over Fireballs or Frostbolts you have after Sapphiron has played through her entire deck (You’ll have one if you’re lucky).
Most of the damage comes from the Pyroblasts and the combination of Feugen and Stalagg.
Feugen and Stalagg don’t do much on their own against Sapphiron. She’ll just destroy them same as any other minion at the start of her turn.
But because they die on her turn, Thaddius is also summoned on her turn. Then when your turn rolls around you can attack with Thaddius for a big pile of damage. In a pinch Thaddius can also take out a minion.
But two Pyroblasts and one Thaddius is only 31 damage. Where’s the other 14 coming from?
Hopefully from the latest Mage additions in Naxxramas, the Duplicate secret. The Duplicates should be played when Feugen or Stalagg are about to die.
When the little golems die, you can play them again to summon their big brother once more.
If you play the Duplicates for Thaddius, then you can still play him. Unfortunately, Sapphiron will destroy him before he gets the chance to do anything.
The same thing goes for combining Duplicate with Mirror Entity, so watch out for that as well.
The deck may not work on the first try, but I can assure you that it does work. Give it a try if you’ve got the cards!