Hearthpwn

This my GVG-take on a control mage: The Copy Control Mage.
Top ladder results: Rank 4 + 1 star

There main mechanics are:
Sludge Belcher +Duplicate.
Echo of Medivh + Antique Healbot
And of course [card]Kel'Thuzad[/card] with Sylvanas Windrunner, Cairne Bloodhof or [card]Sneed's Old Shredder[/card] on the board!

Rare mechanics:
Sylvanas + Fireball

The medivh will keep your hero alive, so if possible save medivh til turn 9 healbot combo.
When you have boardcontrol, an early medivh might be very beneficial. Copying Cairne or Sylvanas for instance.

Do not play extra small minons like Zombie or Mad Scientist when Dublicate, Sludgie is on board!

Mulligan for Zombie and Mad Sci in all matchups.
Possible to keep Mirror Entity against Druid, but not with Mad Sci on hand.
Keep Sheep against aggro, obviously.

Matchup considerations
Warrior:
It's often a useful idea to copy your BGH.

Paladin:
Save Flamestrike for Muster + Quatermaster combo.

Rouge:
Usually the hardest matchup, due to Sap bypassing Sludgebelcher/Duplicate

Mage:
Mulligan for aggro, mech mage. If it's freezemage or mill mage. Healbot Medivh combo mostly wins the game.

Hunter:
Do not mullgan sheep or healbot. Healbot is very useful to make Hunter run out of steam...

Priest:
Seize board control but don't over extend into Auchenai + Healing. Always expect Mindcontrol so don't play Sneed or Sylvanas unless you have Polymorf in your hand. KT kan be played anyway, if it gives ju a lot of value the same turn. This matchup often lead to fatigue so try hard to be able to copy your Healbots.