Kaivax, a WoW forum community manager, revealed that WoW Classic's class design, battleground mechanics and stats on existing items will be set to their 1.12 state, despite the game releasing content that expands beyond that. This removes "progressive itemization," so if the stats on a specific piece of equipment was changed during the original updates, that won't take effect in this version.
This is another one that will most likely be a boon rather than a bane to the player base, though time will tell just how 14years of experience will affect the economy of Classic WoW. There has been no concrete word on just how AddOns will work in Classic, but if the infrastructure of the game works the same as it does in retail, there is a good chance that most of the mods that work in retail will work in Classic. This means that quite a few people will be running around with a whole host of gathering, crafting, auctioning, and gold making mods. Now, those mods did exist back in Vanilla, but not in the same way they do now, and not as many people had them back then as will in Classic. This will drastically affect how effective the auction house will be, and hopefully will affect the economy as a whole in a positive way. Another thing that will most likely see a large increase in popularity is carry runs. These have steadily grown in popularity since Vanilla, and rest assured with the old 40 man raid size that there will be quite a few “Molten Core full carry master loot ON PST for prices GOLD ONLY” being spammed in trade chat. Whether tokens will be available in Classic has yet to be discussed, but if so it will have an enormous impact on the economy of Classic. This, in addition to the differences I will cover in the next section, will have a pretty large impact on the endgame of WoW Classic.
If a companion dies during the battle, it will need to be resurrected before it can participate in another encounter or be summoned as a traveling companion. Get that pet a medic! Or in this case, a Stable Master. Stable Master NPCs can heal and revive your pets for a small fee, and there is no cooldown on the Stable Master's heal. You’ll find Stable Masters in major towns and cities across Azeroth.

Before we talk about layering, it's important to talk about the sharding technology used in modern-day World of Warcraft. When a zone in the game becomes overpopulated, players will be seamlessly moved onto a different shard, which is essentially another instance of the same zone. It is important to note that you will still be able to play with your friends, because you are moved to the same shard when you create a party.
It is a great advantage to start making some silver and your first gold coin at low levels already. Skinning is a nice choice here. Fast and easy way to gather resources, leather of all kinds while leveling for those who are at the race to level 60. There are many good spots to grind beast mobs and skin them. I like doing it as a Troll Hunter, trolls have a passive racial ability: + 5% bonus damage against beasts.
The vanilla WoW Horde leveling guide you see on this site was originally made back in 2006 by Joana (AKA Mancow, or FuriousPaul).  The guides have been tweaked many times over the years to make things "faster".  The leveling guides were made because of all the messages I got from people asking me how I was able to level up so quickly on new realms.  I was first to level 60 on 7 different realms (3 with Mancow and 4 with Joana), even winning Blizzard's "First to Level 50" contest they held back in 2006.

Before work began on World of Warcraft: Classic, it was only possible for players to experience the original World of Warcraft by using private servers, which are illegal, often have stability or corruption problems, and generally are very imperfect recreations of the authentic World of Warcraft experience. As much as Blizzard has been aware of the desires of their community, until recently it seemed impossible for them to emulate Classic servers due to the technical hurdles of essentially having to run two massively multiplayer online games side-by-side. A breakthrough was then achieved that made it possible to run Classic servers on the modern architecture of current World of Warcraft servers.
Before work began on World of Warcraft: Classic, it was only possible for players to experience the original World of Warcraft by using private servers, which are illegal, often have stability or corruption problems, and generally are very imperfect recreations of the authentic World of Warcraft experience. As much as Blizzard has been aware of the desires of their community, until recently it seemed impossible for them to emulate Classic servers due to the technical hurdles of essentially having to run two massively multiplayer online games side-by-side. A breakthrough was then achieved that made it possible to run Classic servers on the modern architecture of current World of Warcraft servers.
A new quest will pop up once your first pet reaches level 3. It will send you to either Audrey Burnhep in Stormwind or Varzok in Orgrimmar. These trainers will offer a quest chain to battle specific Pet Tamer NPCs on each continent. Defeating each of these NPCs will reward a nice chunk of experience for your pets, as well a Sack of Pet Supplies (which has the chance to drop the Porcupette companion, among the always-useful pet bandages). 
×