Patch 10.1.7: Fury Incarnate
new mounts listed by source
Only two mounts are available at the start of 10.1.7 (both related to Dreamsurges), with more being introduced later in the patch.
Mounts of Patch 10.1.7 by source
It figures that this handsome, purple murloc is scheduled to be a shop purchase.
You can purchase this dark ohuna from Celestine of the Harvest, who appears in whichever Dragon Isles zone is currently undergoing a Dreamsurge event. The Dreamsurge Coalescence required to purchase this mount can be collected from defeating various Dreamsurge event NPCs and empowered rare NPCs, as well as by flying your mount through small, green, floating orbs that appear in random places around the Dreamsurge zone (usually in higher up locations).
While these mounts were added to the database in 10.1.7, it's possible some won't actually appear in the Trading Post until a later patch. We don't know which months they'll appear, but it seems reasonable to assume that Eve's Ghastly Rider will appear around the Hallow's End event, so either October or November.
Pattie is the reward for completing the achievement Whodunnit?, which began with the 'Secrets of Azeroth' event on 30th of August, with the final clue being offered on 13 September.
Miscellaneous Scenario and Instance Achievements
The Sandy Shalewing will be achievable during 'Turbulent Timeways', which is a special kind of Timewalking event in which five different sets of Timewalking dungeons are available over five consecutive weeks. Keep an eye out for when this event starts!
You can create this yellow magmammoth mount by combining 20 Charred Elemental Remains. These drop from the Flame Lieutenant final boss in a Dreamsurge portal event, and also NPCs from sporadic Waking Dream portals in the current Dreamsurge zone.