The rune etchings you obtain during the 3 times a day master expedition quests can be used to obtain the Chest of lost adventurers (after completing the quests for Rhunemaster Sinye). Find Zok under the stairs in Yawning Portal and exchange your rune etching for a box.
Each box will contain 5500 AD and a chance at new mod 16 artefact neck. artefact waist or artifacts, vanity pets including a legendary vanity pet and armour up to 1000 item level. If you are not going to save your rune etchings for upgrading the new Ruined Apprentice Armour that can drop, try you luck with the these boxes.