Hearthstone Game Designer, Matt London, took to Twitter yesterday to celebrate the launch of Book of Mercenaries Cariel to talk about the development of the chapter. If you're interested in development insights, this is the thread for you to read.

Oh, right, spoilers, yo!

Quote From Matt London

To celebrate the launch of Book of Mercenaries Cariel, I wanted to share some fun insights from the development of this chapter! Light spoilers below. I hope you'll follow along!

Which came first, the chicken or the easter egg? In this case it was the egg. As the cast for Year of the Gryphon shaped up, we realized it was critical that our warlock mercenary hail from Stormwind (for United in Stormwind)…

…But she also needed to have had run-ins with the Scourge and Kel'Thuzad (for…other reasons). An education at Scholomance Academy was the perfect backstory for Tamsin, so we let Judicious Junior inform our Tamsin design.

It was very exciting for the team to bring a diverse cast of human characters center stage in Year of the Gryphon. We worked closely with Blizzard's DE&I Network to ensure that while these characters had flaws and complex inner lives, we didn't slip into stereotypes.

The flashback/dream in Fight 1 was the first battle I concepted at the outset of design. It shows how war has transformed these women, changing character class, body, and purpose. The scope of WarCraft is so big, I wanted to explore how everyday Azeroth folk were impacted.

Fight 1 also gave us the chance to see a younger version of Cariel. Kudos to Moon Colony for the incredible work they did on this portrait – one of my favorite art pieces from the year.

This POV pivot on Dreadmist Peak was key to the story. Tamsin is the final boss in Kurtrus's book, and Kurtrus is the first boss in Tamsin's. Two chapters later, we see the aftermath of that duel, with Cariel reckoning with her choice to stand against her friend Kurtrus.

One of the big creative challenges for Book of Mercenaries was creating fight variety without much eng time. We tried to leverage existing tech from past adventures. In Fight 4, we remixed the "Take Flight!" tech from Belnaara in Dalaran Heist with light tower defense mechanics.

Fight 4 also highlights one of the cool collaborations Book of Mercenaries did with the Set Design team. As the questlines were developed, there was a lot of creative brainstorming between us. In some cases, like "Defend the Dwarven District," the Book of Mercs plot came first.

In other cases, like "Raid the Docks," the card design guided the story, and led to that awesome Hooktusk cameo in Tamsin's chapter.

A little game I play with myself: how subtly can I make references to other Blizzard IP? My favorite so far is Xyrella's "Heroes never die!" Her delivery is awesome. But these are strong contenders.

There are a number of Mass Effect alumni among the voice cast in Book of Mercenaries, most notably Tamsin (Kimberly Brooks), Rokara (Courtenay Taylor), and Guff (Fred Tatasciore). But Xur'gon might be the most surprising of all. Any guesses who it is?

And yes, I was starstruck recording of Book of Mercenaries. Blizzard gets the absolute best actors in the business, and if you'd told me that Wakko Warner, Zeratul, Balthier, Noctis, and Winnie the Pooh were all going to appear in a game I worked on, I'd have lost it.

These Fist of Anetheron minions really give a sense of the scale of the enlarged dreadlord. I love the idea that a character is so big and powerful that it has to be represented by more than one thing. Shoutout to Kurtrus's Fay Wray impression.

We had a challenge to show ten story arcs when 90% of the journey would be from another character's POV. For the Anetheron fight I wanted to show its importance by flexing many unique Book mechanics: Merc as Hero Power, Merc as Super Minion, and Multi-phase boss fights.

huge shoutout to Nondumiso Tembe who rocks it as Cariel. She takes her role so seriously and has a ton of fun as well, whether that's delving into her character's psyche or shipping Cariel with the other mercenaries.

Time to take a break. I'll follow up after you've had more time to play through the adventure. Book of Mercenaries has been an absolute joy to make. If you liked this thread, please retweet and follow. Guff will thank you with a tauren high five! (With his hoof.)