War mode is essentially a toggle that allows players to switch PvP mode on or off at will, regardless of what kind of server they are located on. Players who complete quests with War Mode turned on will reap additional rewards. Players will also have additional PvP talents that are only active during War Mode. With no flying in Battle for Azeroth until next year most likely, this could make running into a player of the opposite faction exciting and nerve-wracking again.
Players who were around during Mists of Pandaria might recall a dungeon mode called Scenarios, which involved teams of three players instead of the traditional five. Island Expeditions bring a similar feel, with groups being tasked with plundering treasure off various islands. Your team faces off against other players or AI-controlled characters from the opposing faction and whoever can collect the most treasure, or "Azerite," wins.
Level with a pet if you can because it will help keep you safe. If your pet is tanking all of the damage from the enemies you’re fighting, you won’t have to. The other reason is that pets are easier and cheaper to heal than you are. If you don’t have a pet, make sure you know how to use your defensive abilities. You can’t level quickly if you are dying all the time.