Part 2: Anub'ReKhan
As for the first boss in Heroic, Anub'ReKhan, He was fairly easy as well. I dont even think I changed my deck and I beat him on the first try too. The only problem was managing his upgraded hero ability, which was taxing considering for 2 crystals he can have a 4/4. He also has more cards in Heroic Mode.
Part 3: Maexxna
This gargantuan beastly spider god was 100 times harder than I expected as compared to the other two bosses in the Arachnid Quarter. His hero ability is stupid tough to manage at first sight, plus he starts out with 2 Haunted Creepers on the board.
Here's a look at the Hero ability comparison:
I found that the trick to this boss is to manage all of his minions because he will be putting out a lot of Haunted Creepers. There are various guides on the internet detailing how to do it and what the best class match up is, but since Priest is my favorite at the moment, thats all I used in the Normal and Heroic versions.
The deck I used was mostly spells. I deleted all of the decks I had made to try and beat him in the 4 hours of play time (It took so long because I was trying to adjust to the crowd control factor on his mobs), but here is a recreation of it:
I found that using low cost cards with some sort of healing or damage Battle cry was the most viable option for Minion Cards such as:
Maexxna is going to 99% of the time use his Hero Ability first thing and send 2 random cards back to your hand (and it doesn't matter if they are "Stealthed" cards or "Cannot be targeted by Hero Abilities" cards, he can still send them back, which was one thing I didn't realize the first hour and a half), so essentially you can use the 1 damage or 2 health for free every turn if you wanted to.
Those coupled with 2 Wild Pyromancers made crowd control a cake walk, especially in combination with Holy Nova Made taking care of the Haunted Creepers and Emperor Cobras and Dire Wolf Alphas.
Its good to let his side get full a bit while you use the Elven Archer and Voodoo Doctor to get the spiders and wolves down or at 1 hp during the first few turns, stack cards and then when your are ready to unleash the Wild Pyromancer and Holy Nova combo make sure his mobs are silenced so nothing respawns. Then you will use low level cards that spawn an extra mob, which will get sent back to you hand at random, 2 at a time. If you use Murloc Tidehunters the Murloc Scout he spawns costs 0, you can put those boys on the board all day long. He should end up using his whole hand and only have 1 card per turn plus his Hero Ability, once your're that far, you can demolish him.
There is no in-game reward for beating the wing on Heroic, but you atleast accomplished it and got all of the cards from Normal mode and the Class Challenge mode.
Thanks for reading, if you have any questions or comments, feel free to drop a line!