Jun 4, 2022, 22:0906/04/22
You need gauntlets, chestplaye and boots that have ATK % as their main stat. If you highlight an item in your collection, the main stat is is at top, followed by substats beneath it, if their are any.
If the challenge is indicating that you already have done this with 1 champion, then you know its working correctly. You just need to do it again with 2 more. If you cant find the champion you equipped them with before, for whatever reason you are, you could have fed them.