Hearthpwn

...just like they do in standard.

It took around 70 packs (from the legendary before it) to get the last of the newly released legendaries. Fortunately, I had 250 packs saved up, so I got her (Ysera) in the end, but it sure felt horrible burning through them for the sake of one missing legendary, and knowing there was a chance I could open every single pack I owned and still not find her.

I hope that Blizzard addresses this in the future.

Well, what an annoying surprise.

At the end of the first questline, about 6 bounties in, the reward is a legendary card. Had I known that I could have saved 70 packs, but instead I got a portrait I didn't need on account of having collected every merc.

Well, it seems like I'm gonna hold this questline until another new mercs are released... Didn't know about it and opened packs as well

Honestly, this is one of the worst modes for collecting. It could use some tlc to keep people interested. 

I agree. And not only for mercs, but for their skins as well.

I mean, just think for a second I would want something like a platinum skin. The odds of getting a legendary skin are minimal, and the chances of that skin to be a platinum one are even more scarce, and then, only then, it has to be for the hero you want. I mean, I'm cool if you want to have people spend cash on this stuff, but even spending cash your chances are minimal.