Hearthpwn

Yes. This is a detailed thesis about the power level of Genn Greymane and Baku the Mooneater. Yes. I will write about which is better as a card, and as a multitude of archetypes for decks. This is a deadly combination of spare time and passion to write. This is geared towards experienced HS players but is written to be understood by all. Lastly, this was written BEFORE Rastakhan's Rumble was released. I did not attend Blizzcon, so I have not played any preview Tavern Brawl or anything of the sort. HSReplay is my main source.

Genn Greymane is a 6 mana 6 attack/5 health neutral legendary from the Witchwood set. With this in your deck, your hero power will cost 1 (instead of 2) mana assuming all cards in your deck are even. This effect occurs AFTER the initial mill phase. You can theoretically have 4 odd cards in your deck, and still have Genn's effect trigger (Assuming you draw them). You CAN have a quest in the deck and always get Genn's effect to go off, as long as you keep the quest in your opening hand. If Genn is in your deck and you do not meet the all even cards condition, no animation will occur. If you do meet the condition, your opponent will know. If you change your hero power at all, the cost reduction does not stick.

Baku the Mooneater is a 9 mana 7 attack/8 health neutral legendary from the Witchwood set. Similarly to Genn, if your deck only has Odd cards, your hero power will stay at 2 mana, but is upgraded. The upgrade to your hero power is the same that would occur with Justicar Trueheart. 

I to remember which is which, I use the trick "Deck is even, hero power is odd and vice versa."

Now for the actual analysis.

The cards themselves are pretty bad. They essentially have no text on the card. For no text minions, I use the formula (H+A)/2M=P. A minion's health and attack divided by twice its mana cost equals its "power level." So, an "average" power level for a blank card would be 1.0. Putting the minions on trial, Genn pulls a 0.916. Baku pulls a mere 0.833. So both of these cards are bad by themselves, but Genn is a slightly better drop than Baku. I don't consider this into which is better because you will put them in their respective decks anyways. 

Next, we consider the power of their effects. 

There are 4 main Odd archetypes. Paladin, Rogue, Warrior, and Hunter. Even decks have 3 meta spots, with Paly, Warlock, and Shaman. Odd Paly has been the top of the meta for what seems like most of Boomsday, with Odd Rogue, Even Paly, and Even Shaman coming in at second through fourth places in varying orders. Odd Rogue occasionally pops up above Odd Paly, but only occasionally. Odd Warrior is a solid deck but only holds a tier 2 spot. It is a Whizbang deck, with the taunt quest. Odd Hunter isn't even that solid of a deck, it depends on a good draw and is just a super aggro deck. 

We'll go more into depth with Paly, as it is the only class with tier 1 even and odd decks. Even Paly's strength is the ability to hero power on most turns. It has a flexible curve, with a hero power on most turns. Odd Paly's strength is that it floods the board with its hero power and it has more synergies with its wide board. Also, Odd Paly's synergies are strong with a wide board of silver hand recruits but can work with any wide board. Raid Leader can work with any minions, while Lightfused Stegodon only affects silver hand recruits. 

One more thing that I want to point out, In an Odd deck, you can play Raza the Chained. It is unrealistic to have an odd unique deck, as you are passing up on Reno Jackson and Kazakus, but I wouldn't be surprised to see HysteriA do some BS world record combo with it.  

Moving along to a conclusion, 

Overall, both Genn and Baku's effects are powerful and meta-defining. Each can be played in its own way (Odd Warrior is Control, Odd Hunter is Aggro, Odd/Even Paly, Even Shaman, Even Warlock and Odd Rogue are midrange). I can't label one as straight-up better than the other because of the variance in hero powers. 

I've seen Even and Odd Mage. Both are off meta and similar in power level. I rank Odd mage over Even Mage because of the cards, not really the hero power. 1 mana deal 1 damage is pretty equal to 2 mana deal 2 damage. 

Druid is similar to Mage. Druid has so little odd/even decks that it doesn't show up on HSReplay. I can't say that Even or Odd is better because they both suck on here

Hunter is a no-brainer. Odd hunter isn't a top tier deck but is probably the most aggressive deck. Most aggressive minions (Hunter and Neutral) are odd, so there you have it. 

Paly is a toss-up because both Even and Odd paly are top of the meta. I like odd more, because I played it as my first deck this expansion, but I'm not picking favorites. So this one's a draw.

Priest is with druid, I never see even or odd, so no contest.

Odd Rogue is top tier, so that's that.

Even Shaman is top tier, and it's the only tier 1 or 2 shaman deck, so there ya have it.

Even Warlock has the ability to get an 8/8 giant out onto the field on turn 3, another on turn 4, and a 4/10 dragon on turns 5 and 6. The upgraded hero power is just really bad, so Even blows this one out of the water

Odd warrior was going strong for a while but started to die down around the middle of the expansion. Even never competed, so Baku wins warrior.

There ya have it.

Thanks for reading this disorganized Charlie Foxtrot of a thesis.

Here are all the possible minions you can get

Even without the spirit, Weasel priest just got a lot better

I think that Healing rain is used to heal minions very infrequently. in 99% of use cases, it would be better if it said "Restore 12 health to your hero."

Healing rain is pretty ridiculous. Healing Rain is basically Ice Block unless your opponent has that extra damage. But in that case, an actual Ice Block probably wouldn't have saved you anyway. I think Healing rain should be 2 mana restore 10 or 4 mana restore 12. (I lean towards 2 mana restore 10). 

As for Branching Paths, I understand your problem against it. 4 mana 12 armor is good, but I see it more used as 4 mana draw 2. Whenever I see it used for double armor, it's just a desperate move to stay alive. I rarely see double armor taken to double charge the druid spellstone, because most druids will take Malfurion and hero power every turn, taking armor unless a trade is absolutely necessary.

Combo decks can't really be nerfed by hitting deck filler. If Team 5 nerfed Branching Paths instead of Aviana, AK-47 Druid would still be running rampant on the wild ladder. The only deck where Branching Paths is a cornerstone is Hand Druid, and it always draws 2. 

For the first time in my HS Career, Spellbender is put to use

If you use a card with overkill, and you deal exactly enough damage to kill the minion, the overkill effect happens. Not Every overkill effect, and not triggered by cards without overkill. Sorry I couldn't get the art, but this is just my guess.

Ragnaros, Lightlord commands you to LIVE INSECT

Mana Bind will get me a copy, just for safe keeping

King Togwaggle flips the fatigue counter on you

The Servant of RNjesus swoops down but deviates from instructions, giving you a chance to not get screwed by RNG

Are we permitted to use the new mechanics that will be released with rashtakan's rumble?

Hard to say anything about this card without more reveals. Its power level will increase with pirate synergies, weapons with lots of attacks, and board fill synergies (such as Knife Juggler

No twilight drake is surprising, but makes a bit of sense