First Wonders

Easy way to get this achievement:
1) Collect Sandworn Relics doing Zereth Mortis content.
2) Buy gear with the relics from Rafiq in Zereth Mortis. The relic prices for all the pieces you can buy are as follows:

160 - Cloak, Bracers, Belt
230 - Boots, Gloves, Shoulders
300 - Chest, Head, Legs

You will need a total of 2,070 Relics to buy them all on one character.
3) Use the Creation Catalyst to transform the pieces into LFR version pieces for the slots you are missing the transmog appearance.
4) Achievement done.

FYI, you can also convert Shadowlands mythic dungeon items into tier set items at the catalyst.

Confusing achievement when it doesnt list which Items I lack ..

Ive got a full mythic set including tier, but no achievement ... sigh, wtf ?