So 12 1 drop 1 2 drop 7 3 drop 5 4 drop 5 5 drop So an average 2.7 mana card
If we count all the legendaries from the year of the raven and classic cards we have 3 1 drop 6 2 drop 9 3 drop 9 4 drop 13 5 drop 12 6 drop 15 7 drop 15 8 drop 13 9 drop 6 10 drop + shirvallah so we have an average of 6.1 mana card
Sure there are crappy legendaries but most of them are gamebreakers contrary to all the rest of your aggro decks. So its an insane upgrade in the late game and it will be so strong if you can play rafaam turn 7 and take advantage of your warlock hero power to draw some insane legendaries.
I'm somewhat surprised people are actually saying this card is bad. Not specifically in Zoolock (which it doesn't really fit the deck that well) - but in general. It's an even better version of Elise without the awkward set up. And the monkey was a great card already. Even without it's ability it's still 7//8 taunt for 7 which is pretty good.
Seems to me that many people have a hard time getting the current aggro / mid-range / otk meta out of their minds. The year of the dragon meta is unknown. Judging by the legendaries and other cards revealed thus far, it seems like the devs intend control to be a thing. If control is a thing, then this card is definitely a thing, Elise has proven that before..
The thing about Zoo-Rafaam is....why not Jaraxxus?
I actually played Zoolock with Jaraxxus during early RR to counter Odd Warrior (which worked a lot better than expected), but at its core it just wasn't worth it. The thing about adding a slow late game value option to a fast aggressive deck is the same that plagued Hunter for the entirety KotFT: If it'S not consistent it will often end up as a tempo loss or dead card. Only after Rexxar got buffed via poisonous and lifesteal beasts did it become as good as it is now.
Same goes for Rafaam/Jaraxxus/Bloodreaver Gul'dan in Zoolock. IN most cases it's not a card you want to topdeck if you are trying to outpressure your opponent. I'd say Rafaam's saving grace might be the fact that he has taunt, which shouldn't be ignored.
In the end, people will run this whether it makes sense or not, because let's face it, the card is fun.