The Hearthstone Deck I am focusing on this time around is Odd Mage. It is a really good deck that I don't think gets enough attention because of the DOMINANCE of Hunter, Paladin, and Priest. It is a solid aggro deck that can also play as a somewhat control if it needs to due to its hero power and some of the spells. It has a great late game because it is the only class with access to Ragnaros, which previously was deemed to OP to see play but now is available for 7 mana... The deck revolves around good 3 drops and decent spells and the deal 2 damage hero power that can combo with some other cards to do super large amounts of damage out of nowhere (Clockwork, Daring Fire Eater, Hero Power for 8 damage).
Matchups: It is fast enough to deal with control decks a lot of the time (primarily Priest either Control or Clone) and has direct damage so it can beat warlock as well. Play these matchups as fast as you can and hold nothing back (especially the 3/4 cause it can usually survive removal). Into Hunter you can bait out some secrets with small minions and this deck will get a buff when the Spellstone is nerfed cause it has always been somewhat difficult to deal with (although not impossible with cards like cinderstorm and if you have a counterspell). Paladin is rough but keeping Cinderstorm and Arcane Missiles is a good keep to deal with wide boards into odd, and your fast pace beats most control and OTK Paladins.
Mulligans: Keep at least a 1 drop (maybe more) and potentially some 3 drops as well. If you have Tor Mage and a secret keep that for sure for the extra value but if not many of the other 3 drop minions will be just fine due to their pretty good stats and abilities. You can also keep the dragonhawk into control if you want because it is a lot of surprise burst damage on 7 (or 6 with coin) and forces them to have removal. Into aggro though don't keep it but DO keep spells like arcane missiles and cinderstorm to help against wide boards and let your hero power clean up the rest.