Best Deck to Beat Gothik the Harvester in Heroic Mode
Gothik the Harvester plays many cheap minions that are hard to beat if you also aim to summon minions. Therefore the best deck to use is one that doesn’t rely on minions and can stop the incoming damage. A version of Freeze Mage which is shown below is the best deck to beat Gothik the Harvester in Heroic mode. Others that would also work is Handlock and control decks.
Best deck to beat Gothik the Harvester:
2x Ice Lance
2x Acolyte of Pain
2x Arcane Intellect
2x Frost Nova
2x Ice Barrier
2x Ice Block
2x Earthen Ring Farseer
2x Cone of Cold
2x Azure Drake
Best Strategy to Beat Gothik the Harvester in Heroic Mode
Play Freeze Mage as you normally would focusing on stopping incoming damage using Frost Nova, Blizzard etc. Play the two secrets when you can to ensure that you can survive for a few turns after summoning Alextraza. It is essential that you play turn 9 Alextraza and kill Gothik the Harvester in turn 10 and 11 using Pyroblast, Fireball, Frostbolt and the other burn spells. Note that it might take you a few attempts and a good starting hand to win. A good starting hand would be some secrets and the delaying tactics.