Hearthpwn

Mulligan:

Mirror Image, Murloc Tidehunter, Mirror Entity, Mind Control Tech


Combo:

Murloc Tidehunter / Dragonling Mechanic + Mirror Entity + Frostwolf Warlord

Tactic:

Try to clear the board as good as you can and get some high-stat Frostwolf Warlord or mirror Deathwing. Because he has no removal you can defeat him in a few rounds of facedamage form this point on.


Swaps:

Mind Control Tech: Nothing. Sorry, but i think at least one copy of it is mandatory. But of course you can throw out any minion you want for another copy of it. If i had a second i would definitely do that.
You can swap any other minion with a card of your choice that provides early/mid game board control or prevents your death before you get to your Warlord or Deathwing. A few examples would be :Doomsayer, Annoy-o-Tron, Sylvanas Windrunner, and so on. 


Final Thoughts:

You may need more than one try to get a decent enough card draw to defeat him. Keep in mind that this is an budget deck so don't get frustrated if you lose on the first try, it is definitely manageable to win this heroic encounter with this deck. Good luck and don't forget to have fun!