If you have Overwatch and an Amazon Prime Membership, you can get a free in-game Golden Loot Box with a guaranteed legendary item today, plus five extra standard loot boxes, and then five more in October, no grinding required.
This gift is free for all Twitch Prime members, which is included with a standard Amazon Prime membership. You can find the details, and sign up for a 30 day free Prime trial if necessary, on this page.