Between April 15th and April 29th you can claim the Thieves Guild DLC and the Treasure Hunter Horse mount for FREE!
Here's how:
Earn (or have already earned) the “Pocket Picker” in-game achievement
To earn this achievement you need to pickpocket ONE citizen in Tamriel -- that's it!
Then, go to the Crown Store and claim the entire Thieves Guild DLC for free
The Thieves Guild DLC grants you access to the Hew’s Bane zone, the Thieves Guild organization and storyline, and the Thieves Guild Skill Line. If you own this DLC you can also claim the Treasure Hunter Horse mount for free from the in-game Crown Store
Here's how:
Earn (or have already earned) the Hew’s Bane Cave Delver achievement.
To unlock this achievement, defeat the delve bosses of both delves in Hew’s Bane
Then, go to the Crown Store and claim your new mount
During the promotion window (April 15-29), some of the Daily and Weekly Endeavors will also feature challenges relevant to both Thieves Guild and Dark Brotherhood members!
If you don’t own or have access to the Dark Brotherhood DLC, you can acquire it during the promotion window for 20% off.