Merchant's Favor is tied to two new Forever factions, the Azeroth Commerce Authority and Durotar Supply and Logistics. Blizzard has said very little about it, so most of what you'll read elsewhere is from the beta.
What Blizzard has said
Confirmed from Blizzard's Legacy System post:
- These are two new Alliance and Horde factions, and "a major source of new tradeskill activities".
- A Legacy perk called Performance Bonus sometimes gives you more Merchant's Favor from them.
Blizzard doesn't say which faction belongs to which side. Durotar is Horde territory, so we'd assume Durotar Supply and Logistics is the Horde one. That's a guess.
How you seem to earn it
Unverified, from beta players on Blizzard's forums:
- A player's copy of the perk's tooltip mentions gaining favor when you hand a crate in to one of those factions. So crates are the likely source.
- Another player asks about recipes bought with crates, which suggests those factions offer recipes. That's an open question in the thread, not an answer.
What goes in a crate, where you hand it in, and what the favor buys are all unknown in what we've read.
What to do until we know more
- Train at least one crafting profession if you want to try this. Blizzard links these factions to tradeskills.
- Look for the factions' agents around your capital and early zones. We don't have a location yet.
- Keep crafted goods and materials rather than selling them all at first, in case a crate needs them.
Bartering is another Legacy perk nearby: it reduces vendor prices, but Blizzard fixed it so it doesn't discount training or repairs.
We'll write up the crates, rewards and locations once we've done them, on the reputation page. If you've turned one in on a live server, leave a comment on that page.