Blizzard Entertainment is inviting players to help with the testing phase by copying their characters and downloading the Public Test Realms client.
The Thunder King offers players a new daily quest hub called The Isle of the Thunder King, a new raid called Throne of Thunder, three new world bosses and a new world boss system.
The patch includes creature changes such as three new tameable spectral porcupine spirit beasts, Dire Horns are now tameable species for Hunters, and defeated Zandalari Warbringers drop crafting materials, reputation gains, an achievement, and a chance to get one of three new rare mounts.
Pet battles have a long list of changes. Big changes include new rareBattle Pets and pets that die in battle never respawn. New pets can be located on the Isle of Lightning along with rare spawndrops, wild pest and raid boss drops.
The patch includes new quests; Walrocks who have the Codex of Xerrath can do a solo mission where they can change the color of Fire Spells to Fel Green. Characters who reach level 20 and level 60 can chose to do a quest to go to the racial riding trainer and mount vendors.
Along with an extensive list of class tweaks, there are several bug fixes for classes; for Druids, a weaker application of Living Seed can no longer overwrite a stronger one; for Warlocks, Demonic Circle: Teleport now shares the same cooldown when in Metamorphosis; for Mages, when they enter an arena, the cauterize cooldown will now properly reset; and Paladins can no longer refresh inquisition to a lower duration.
For Macs, the issue that would cause command-left-click to occur as right-click while using the trackpad is now fixed and the Logitech LCD applet for G19/G15 keyboards will now launch with the 64-bit client.
Current patch notes are not final and can be viewed in full on the official World of blog.