War Mode: War Mode can be turned on at level 30 through your talent window, and will give you 10% bonus XP. You will, however, be attackable by players of the opposing faction, but changes have been made so that all players have a fair shot in a fight and even low-level players can kill much higher level players, and at least not get ganked and one shotted. Note: As of patch 8.1, you can get an additional call to arms bonus with war mode on if your faction is underepresented.
Each of those modes existed long before this latest expansion; raiding is a basic concept in MMOs, and Mythic+ was added in World of Warcraft’s last expansion. The problems with Battle for Azeroth’s endgame come from the systems it adds, which most often artificially gate progress where most of the fun can be found. If raids and Mythic+ are the carrot, we’re about to talk about the stick.
As for the classes themselves, they almost all play like slower and slightly less interesting versions of their Legion counterparts. This is thanks in large part to the loss of one ability from each class that came along with Legion’s own AP dumping system: the artifact weapon, which added a unique ability to every spec in the game. The loss of these abilities left most classes feeling frustrating and incomplete, and though Azerite gear was supposed to be the replacement, it missed the mark completely. There will always be one Azerite trait that reigns supreme for each spec, meaning that the frustration of that particular loop will be unavoidable as long as the system is in the game.
The WF/TF system complicates gearing a bit, as you could get an Uncommon quest reward that forges to Epic quality (not a myth - it happened to me on the first night of release). This means that the old ‘Best in Slot' system is, to all intents and purposes, useless, and you should generally opt for whatever item you have that is the highest level - especially as tier gear no longer exists.
Sometimes that requires players to earn gear to give them greater powers that they haven’t yet unlocked. That sense of progression is at the center of what makes World of Warcraft great and so successful over the last 14 years. There should always be a balance between gaining gear and strength through lower-level content and taking on the hardest challenges the game has to offer. With Battle for Azeroth, Blizzard has missed the mark. Getting to elite status just requires grinding content that isn’t fun, instead of players demonstrating their skills.
At 96 the standard wisdom is to immediately drop what you're doing and proceed to Spires of Arak and do the quests to unlock the Inn, granting a further 20% experience bonus while in that zone. You'll want to do that eventually anyway, but I'm not sure it outweighs the quest experience from Gorgrond. However, if you decided to go to Spires immediately at 96, restrict yourself only to bonus objectives and again leave Treasures until you're 100+. Make certain that when you being the quests to unlock the inn, you speak with the quest NPC to also learn Archaeology, since it's required to collect several of the treasures in Spires.
Was doing it at 52 on my lightforged paladin and it was easily the slowest zone out of the ones I'd done. Granted, I didn't have War Mode on so I didn't have any PVP talents, but it felt like about 40% of my time was spent waiting around for respawns or wandering around looking for mobs to kill to get a quest item that had like a 5% drop rate. Maybe I just got unlucky but I definitely won't be going to that zone again for future heritage armor runs.
-Warfronts- I liked the idea of warfronts because it blends elements of Warcraft III with World of Warcraft, however, it's not a PvP battleground or instance, it's PvE so given time, it's a guaranteed win so many people are starting to AFK in the warfront. Beyond that, there is only one warfront to participate in right now. Also, when preparing for a warfront, Blizzard presents you with daily quests to help "aid" the warfront, however, your daily quest turn ins have no bases on the progression of warfront. The warfront will continue to advance at the same rate no matter if you do zero quests or everyone does all the quests.
Allied races aren’t much better. You can only earn them by grinding out reputation. It doesn’t take that long but casual players will need to invest a couple weeks primarily to it, and focusing on that grind will take you away from others, like earning gear. Each race has its own grind, but the things you do to work through it remain the same, adding to your boredom.
Elixirs serve the same purpose as Flasks, but the buff expires if you die. You'll only use these between 1-70, generally speaking, until you can start buying Flasks which persist through death. Try not to die, and carry extras just in case. If you can't find an Elixir with the stat you want, look under scrolls, since they count as battle or guardian buffs as well.
You should try and quest efficiently - pulling several mobs if you can handle it, using your burst cooldowns while questing to kill everything faster. Many people would think that a 10-minute cooldown like Bloodlust is useless in open world, but you can do a "kill-15-mobs" quest in like 30 seconds if you pull a lot and use it. A free quest every 10 minutes is not that bad.