WowAce

r678:

Added tracking for the remaining collectibles (pets and toys) dropped by rares in the Arathi Highlands
Added tracking for both toys obtainable from the Arathi Highlands world bosses (Doom's Howl and The Lion's Roar)

Existing mounts that are obtained from killing rares in the Arathi Highlands are now correctly listed under the "Groups" category if they're difficult to kill alone

Luckiness calculation for the mounts dropped by rares in the Arathi Highlands now correctly ignores group size
Statistics tracking for the mounts dropped from Mythic difficulty dungeon bosses in The Underrot, Freehold, and King's Rest should now function properly

Known Issues:

Looting a Challenger's Cache in The Underrot, Freehold, or King's Rest (Mythic Keystone difficulty) doesn't currently add attempts for the mounts that it can contain
Defeat detection for The Lion's Roar is not currently implemented (see notes below)
Defeat detection for Knight-Captain Aldrin doesn't currently work (ditto)
The drop rates for many, if not most, of the new items are likely inaccurate. They will have to be updated once more data is available

Developer Notes:

I don't have a Horde character at max level. Someone will have to find out the quest ID - feel free to message me for instructions on how to do this (it's quite simple if you haven't killed the boss yet for a given warfront cycle)
It is unclear whether or not the toys from Arathi Highlands world bosses can be obtained via bonus roll. Please let me know if someone has obtained them after using theirs. For the time being, Rarity will not consider bonus rolls to be valid attempts, which may or may not be correct.

r677:

Added tracking for all collectibles obtainable from Island Expeditions (see notes below)
Added item: Viable Cobra Egg (Drop: Merektha)

Reverted a minor cosmetic change to the addon's output that had harmless, but unintended, side effects

Looting Nok-Karosh should no longer count attempts for the Eye of Observation pet (which is a drop from Orumo the Observer)

Developer Notes:

Since there's virtually no data on anything regarding these items right now, most estimates are little more than a wild guess. They will need to be refined in future updates.

r676:

Added tracking for mount: Hellfire/Felblaze Infernal (Drop: Gul'dan)
Added tracking for mount: Shackled Ur'zul (Drop: Argus the Unmaker)
Added tracking for mounts that will be obtainable from killing the Warfront: Arathi Highlands rares (see notes below)
Added tracking for mounts obtainable from Mythic difficulty BFA dungeons

All Warlords of Draenor raids are now considered soloable
Midnight's Eternal Reins: Attumen the Huntsman is now considered soloable
Updated group size estimations for various Legion raids

Mouseover tooltips for the Assembly of Iron encounter in Ulduar should once again display tracking data for Stormforged Rune
Fixed TomTom waypoint creation for some rares on Argus that previously had invalid entries
Looting Frostdeep Cavedwellers in the Horde garrison should now correctly add attempts for the Riding Turtle mount

Developer Notes:

Since there isn't any data available, it's virtually guaranteed that the drop chances for these items are wrong. They will be corrected in a future update.
Defeat detection for the new rares is also not yet implemented.

r675:

Added tooltip for the "Adventurer of ..." exploration achievements to all relevant rares in Kul'tiras and Zandalar

Fixed tracking for Stormforged Rune (Drop: The Assembly of Iron)

r674:

Added tooltip for the "Commander of Argus" achievement to all relevant rares on Argus

Fixed tooltip display for Fossorial Bile Larva (Profession: Skinning)