Template:Heigan the Unclean strategy
Normal and Heroic tactics work out to be roughly the same. Heigan's Eruption has no effect when your side has no minions, so creature-light decks, such as Freeze Mage, work especially well. However, decks that have resurrection-on-death minions, such as 
Nerubian Egg, Haunted Creeper, and 
Harvest Golem, do just fine. The health-gaining effects of Stoneskin Gargoyle, Questing Adventurer, Gruul, and Ethereal Arcanist make them into effective meat shields until a friend can step into the way of the fire.
Try to be ready for minions that are one cast away from appearing on the field. The Voidcaller trigger frequently replaces a 3/4 with a larger threat, and Doomguard will charge across with no warning as early as the fifth turn. Doomsayer deals with Voidcallers quite well, since he will pop them at the beginning of your turn, when you have the most mana. Taunts and armor can take care of the rest.
Warlock is one of the only two classes capable of removing the initial Voidcaller in Heroic Mode before your turn 2, by means of either Corruption or Soulfire. Druid is the other, using Naturalize. A warlock deck with plenty of directly damaging spells and removal such as the above and Shadow Bolt, Drain Life, Siphon Soul, Demonfire etc., as well as resilient Taunts, resurrecting minions and health-gaining or health-restoring minions will defeat him easily even in Heroic Mode given a decent opening hand.
With the Grand Tournament expansion, this battle can be pretty easy if you place 
Dreadsteed in the left-most position, because Eruption will be unable to kill it and thus protect the rest of your minions from the damage.
Decklists
- Hearthpwn.com - The Plague Quarter Heroic Boss Deck Guides
- Hearthhead.com - Decks for Defeating Heigan the Unclean
This template contains Strategy content for these cards.
Remember that this is just an archived content of Strategy section that was supposed to be removed following the decision in Hearthstone Wiki:Project 13. It's up to you to review the content and keep them for a project in the future. Details to follow soon, once Project 13 is completed.