Update: World of Warcraft's next major expansion is called 'Legion'.
The expansion shifts the action to The Broken Isles, as the Burning Legion call forth their fallen leader Sargeras, Ravager of Worlds.
The Broken Isles are said to contain lush forests, huge mountain ranges and night elven cities.
In addition to a new zone, the expansion introduces the new melee-based Demon Hunter character class, which can transform into hellish new forms.
The Demon Hunter character class can also glide into battle and perform double jumps.
Players will receive their own Artifacts, which are class-specific, customisable weapons that increase in power with their owner.
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There's a new Honour system for player-vs-player events, which provides a new progression path.
Elsewhere, Order Halls can be used as a base of operations on The Broken Isles, and to send non-playable followers on missions.
There's also a new 110 level cap, although lower level players will be able to boost one character to level 100 in order to catch up.
Blizzard is yet to reveal the release date, but players can get their first taste of 'Legion' with a beta later this year.
Original story: World of Warcraft's new expansion is to be revealed at this year's gamescom expo - and you can watch it unveiled live right here.
The major update to the long-running online role-playing game will be unveiled at 5pm UK time (6pm European, 12pm ET, 9am PT), so expect a glossy trailer as well as first details.
Follow our ongoing coverage of gamescom 2015
If you want to see more, then tune in again on August 9 at 4pm UK time for a World of Warcraft developer chat before gamescom ends.
A recently-released patch for World of Warcraft opened a new questing zone called the Tanaan Jungle as well as the Hellfire Citadel raid.
The last major expansion to the game, Warlords of Draenor, was released last November.
How has World of Warcraft changed in its first 10 years?
New Hero Class: Demon Hunter - Unleash the demon within as an all-new melee hero class gifted with preternatural mobility - and the ability to metamorphose into hellish new forms.
New Feature: Artifact Weapons - Smite the Legion with legendary weapons of lore. Earn Artifact power to unlock abilities and traits, and customize your weapon to suit your needs.
New Continent: The Broken Isles - Discover the fate of a lost night elf civilization, confront twisted fragments of the Emerald Nightmare, and hunt agents of the Legion in all-new zones.
New Feature: Order Hall - Whether you're paladin or warlock, unite fellow NPC members of your class's order to carry out missions at your command.
New PvP Honor System - Fight for fame, glory, and a range of new PvP-specific powers as you face the opposing faction in Arenas and Battlegrounds.
Boost to Level 100 - Come fully prepared to battle the Legion with a level-100 character boost, and fight alongside your friends in this epic new chapter of World of Warcraft.
