This is the deck I made based on tempo. It allows you to keep refilling the board as long as you have early board against your enemy. So far, it has an around 65% win rate in legend.
Always mulligan for a 1-2 drop minion, preferably a mad scientist or a mana wyrm. You can debate whether or not to keep the unstable portal based on the cards you have in hand already.
Depending on whether or not you have the coin, you may choose to keep the flamewaker because you are capable of dishing out 5 damage @ turn 4 if you have arcane missiles + coin, or perhaps more if you have the sorcerer's apprentice in play.
As long as you have a 1 or 2 drop minion, you should be able to flood the board quite well and win against most matchups.
The issue will probably be freeze mage as they are capable of wiping your board; however, your double fireball and frostbolt should be able to pressure the freeze mage.
You should not struggle against the other form of tempo mage unless you aren't able to clear their board with your flamewaker.
As for mech mage, the matchup may be 50/50 depending on whether the mech mage gets an insane start with mechwarper and etc.
You should be able to do well against control warrior as they require a lot of resources to get through your mirror entity. However, make sure you play around brawl every so often OR only commit most of your minions if you have echo. This will prevent the warrior from gaining too much value. Also, your counterspell is capable of preventing brawl.
You may have issues against grim patron warrior as your flamewaker actually helps against their deck. This means that you have to sustain your pressure against them through your taunts and early game pressure with mana wyrm and etc.
You should be able to do well against oil rogue if you are able to sustain your early pressure. However, if they boardwipe you through bladefury, the game is pretty much over. Depending on the situation, you may want to frostbolt his face to prevent him clearing your board early. The key to winning this matchup is to win early and be able to do 20dmg by turn 6-7.
I am uncertain about this matchup because there aren't as many shamans on ladder anymore. As long as you are able to sustain your board, and can bait out the lightning storm early, you can re-flood the board and slay their totems/minions easily.
However, you should do fine against mech shaman as long as you able to remove their board early through frostbolts, flamewaker, and arcane missiles. The 0/2taunts can also prevent their early aggression and cause them to run out of steam.
You should be able to do well against face hunter because of your spells and 1 damage spells + flamewaker. Your 0/2 taunts can also prevent incoming damage. However, you should be aware of explosive traps as they can easily wipe your board.
You may not do as well against midrange hunter if you aren't able to gain tempo through mana wyrm and mad scientist; however, this is where polymorph comes in and can take out their first big threat (i.e., highmane).
Against control priest, you will want to sustain the board and play around holy nova if possible. You may want to go face in order to secure your win, as priest has a lot of boardwipe opportunities, such as lightbomb, holy nova, and soulpriest + circle.
Against zoolock, you want to maintain pressure through your mana wyrm. As long as you are able to build a board, they aren't able to break through your taunts and be able to make favourable trades. However, beware when they play egg as you can proc it easily with flamewaker and arcane missiles.
Against handlock, you will want to go face as much as possible as they have good boardwipe opportunities. If you are able to make them go to 15hp, you are capable of bursting them with your spells (i.e., fireballs/frostbolts).
Against demonlock, you will want to maintain board presence and make favourable trades. You may want to sheep voidwalkers in order to maintain tempo.
Against control paladin, you will want to sustain your board, similarly to previous cases. You may want to play around consecrate as it can wipe your board easily. You may want to play counterspell early in order to play more aggressively, which means that you should or may want to heavily mulligan for mad scientists. Your polymorph should be able to deal with heavy taunts (such as tirion).
Against ebola paladin (hobgoblin), you just require board presence as they don't have any board clears. Just ensure you take out the hobgoblin and you should be fine.
Against midrange paladin, you would want to be able to clear his board more effectively than he does yours. This means that you want mirror entity taunts up as soon as possible and be able to sustain your damage source (i.e., a snowballing mana wyrm behind taunts).
Against druids, you should be able to do well if you can maintain a strong board. It is okay to flood the board as druids will have issues clearing 2 health minions (they will have to hero power, which wastes 2 mana). You would want to burst druids as soon as possible as they have an overwhelming late game advantage through their taunts and combo.
- Depending on the situation, you may want to go face in order to secure your win. However, it is okay to clear the board if you're against another tempo lineup.
- If you are capable of drawing echo while having a board, it is quite possible that you want to refill the board as you run out of the mirror entity taunts. This will allow your flamewaker to dish out damage as long as you have the 0/2 taunts up.
- You may want to make your opponent think you're a freeze mage through playing loot hoarder and arcane intellect in order to bait out some unnecessary aggression from them.
- When they play kezan mystic, it is alright as you have many small minions and can clear it off with flamewaker.
Cards to be aware of
It is not the worst case scenario for them to steal your mirror entity secret in play because if you use echo, you are able to play the 0/2 taunt as the body.
You should play around brawl or have a counterspell set up before you commit too much against brawl.
You may want to play around explosive trap by committing only weaker minions on board, such as loot hoarder or mad scientists, minions that you want gone.
You should aim for a turn 6-7 win, just like a mech mage; however, you can take it to the late game, but your chances of winning drops significantly if you run out of spells (such as fireballs and frostbolts). You will always want to snowball your flamewaker as it is capable of dishing a lot of damage if they are echo'ed and behind taunts.
You are also capable of refilling your hand if you have a board (with flamewaker) without losing aggression as you can still dish out damage to the enemy and enemy's board.
Feel free to give me your thoughts,