Mulligans
Aggro Mulligans
With the Coin Arcane Blast and Forgotten Torch can be kept.
Otherwise Frostbolt, Flamecannon and Volcanic Potion are very usefull against early threats. Doomsayer also stops aggression very well or at least saves you 7 HP.
A 1-Mana or 5-Mana Kazakus-Potion can swing a game in an instant. The AOE or Single-target Removal are very effective. The Freeze and summon Demon/Minions are also decent.
Midrange Mulligans
We are looking for our Removal to keep our oppenent's board in check.
With the Coin big bodies are very helpfull, like Twilight Drake and Water Elemental.
Combo Mulligans
Again big bodies with the Coin.
Against Priest watch out when using Pyros: Make sure that your opponent can't Potion of Madness and kill it.
Control Mulligans
We are looking for strong bodies, generating effects for more flexibilty in future turns and draw.
Skulking Geist is worth keeping against Jade Druid.
This is my version of a super greedy Reno deck. The dragon package helps with strong bodies in the midgame and card-generation.
The overall strategy is to survive the early turns by removing your opponents minions with burning spells in order to make high-healthed minions stick in the mid-game. From there on you try to keep the board. Because this deck has so much card-generation (Pyros, Ysera, Sindragosa and especially Frost Lich Jaina) it’s really hard to outvalue this deck.
Once your Deathknight is in play things get a lot easier. In order to ease the Water Elemental generation I implemeted cards like Arcane Blast, Flamecannon and even Primordial Drake.
Tech Cards
One super strong tech card is Skulking Geist. It helps in one of the hardest match-ups (Jade Druid).It’s also great against Reno-Priest. Often they run many cheap 1-Mana spells. So you can get them closer to fatigue and reduce their overall burst-potential. It’s also decent against Shaman (Evolve, Lightning Bolt), Rogue (Conceal, Cold Blood, Hallucination).
I chose Meteor over Blizzard as a great removal against big threats like Giants, Jades or a big Edwin.
Sindragosa has the Dragon-tag and works greatly with Deathknight Jaina. And: It feels extremely satisfying/dirty to get a second Kazakus
Substitutions
Reno Mage has one of the tightest lists because of all the different tools and tech cards. So here are some cards that are worth trying or using according to your meta.
Golakka Crawler is great against any Aggro Deck because most of them run Pirates. Almost a must, but just very bad in any slower match-up.
Ragnaros Firelord has great elemental synergy with the Deathknight. Could take the spot of Ysera.
Dirty Rat can kill Combo-decks in an instant. A combination with Polymorph is very powerfull. You could swap Antique Healbot or Doomsayer.