MechaStorm

MechaStorm (Japanese: メカストーム, Rōmaji: Mekasutōmu, literally: "mecha storm") is a mecha-themed skin bundle released on January 16, 2018 which features mecha-themed skins for Abathur, Rehgar, and Tyrael. A legendary Mecha Tyrael announcer was added as well, along with a barrage of mecha-themed sprays and emojis to the Collection.

Background
Leading up to the releases of these skins, Blizzard posted a few teaser images for the upcoming cinematic.

''Mecha Tyrael and Rehgar are squaring off against the insidious Xenotech Abathur in a battle for the fate of the Nexus! Do they have the firepower to save the day, or will Abathur's mechanized locusts prove too much for them to handle?''

''Arm your Heroes with the latest and greatest technological advancements the Nexus has to offer by picking up new Mecha Skins for Tyrael, Rehgar, and Abathur! These Mechas are built tough, with durability ratings so high they're guaranteed to be combat-ready whenever you enter the queue, and come back swinging every time you put them through the ringer on the battlefield. If it's style you're after, our Mechas are crafted using only the finest, artisanal techniques and the rarest materials. With upgraded visual effects on their abilities and altered voiceover kits, you'll be so sleek, sophisticated, and intimidating during hostile engagements that even D.Va will be jealous—Hell, we've even installed custom Hearthstone animations for Tyrael and Rehgar so you can show off even more flair when you need to make an exit.''

Trivia

 * There is an event called MechaStorm II, which began on June 17, 2019.