Weekly Mythic+ record guarantees you 100% an item in the end of the week according to the difficulty of mythic dungeons+ you have cleared on previous week (for example you will get 380 item for mythic+10 in the end of the week);
You will get some of next achievements depends on order you choose:Mythic: Atal'Dazar, Mythic: Waycrest Manor, Mythic: Shrine of the Storm, Mythic: Underrot, Mythic: Tol Dagor, Mythic: Freehold, Mythic: The Temple of Sethraliss;
One of the best ways to prepare for raids;