This is by no means easy and if you are keen on securing that special transmog achievement you'll need an effective approach to farm all 21 fast.

Players who accomplish this will have all Ethereal transmogrify options available for future seasonal and non-seasonal play. Here's what we've been told: Collecting all 21 Ethereals during Season 24 will reward players with the Feat of Strength, Ethereal Recollection. That's 3 each for all 7 classes available in the game. So why should you care? Well, according to the devs you can keep the Ethereal transmogs forever (beyond the end of Season 24) if you find ALL 21 Ethereals available in Season 24 before the season comes to a close. It's worth noting that they are only available to use in Season 24 and you won’t be able to use them with any character in after this season ends. In Season 24, Ethereals take a new form as a new rare and very powerful weapon of choice for your class. Ethereals were a primary feature of Diablo 2, but with Blizzard looking to celebrate the game and the impending release of Diablo 2: Resurrected they've cooked up something new for Dianlo 3.

Diablo 3 farming legendary items