Hearthpwn

I am NOT the author of that deck, but I can't remember his nickname.
My favourite ladder deck, sad that it won't be in standard in mammoth year.
Mulligan: Mana wyrm, Sorcerer's Apprentice, Doomsayer versus aggro. 
Matchups:
very good vs Pirate Warriors (there are some rare cases when they can rush you in the face, but in others you will easily kill them)

very good vs Jade Druids

very good vs Pirate Rogues (same case as Pirate Warrior)

good vs Reno Warlock (but you should keep in mind that you'd better to kill them in one turn)

slightly bad vs Dragon Priest (You can win them , but there will be some difficulties caused by Drakonid Operative

You should keep Thalnos in hand for combos (his role is the same as evolved kobold in freeze mage, but of course there are some game situations when you can play just on board)

Combo's:
Thalnos+frost bolt+Ice Lance+Ice Lance (6 mana, 14 dmg)
Thalnos+frost bolt+Ice Lance+Ice Lance+ Torch (9 mana, 18 or 21 dmg, depends on torch)
You could also use [cardSorcerer's Apprentice ][/card] in OTK (one turn kill) combo's if you use 2 or more spells in a turn.

P. S: Torches and Medivh's Valets might be used not only for dealing dmg in face, but to clear some nasty minions on board (e. g. Tunnel Trogg)