In one look Anima in World of Warcraft Shadowlands resembles Artifact Power and Azerite, but it works very differently from those two currencies. You will not cultivate Anima just to drain it into infinite power. Instead, Anima is used to power a handful of features that aren't directly related to your progress (with one small exception). So if you were worried about Shadowlands being yet another pursuit of infinite power, you can breathe a little easier. However, it's still worth farming Anima while you explore Azeroth's afterlife.
Anima is obtained through items from various activities and quests.
Anima in World of Warcraft Shadowlands comes in the form of items that drop all over the Shadowlands. Whether you're doing world quests, looting chests, clearing dungeons, or beating up your opponents in PvP, there's a good chance you'll get anima from your efforts. The drop chances are different for different activities, but there are several ways to earn anima regularly. Just remember: whenever you want to bank your Anima items and convert them into Anima to spend, you will need to interact with the Upgrades NPC in your Covenant Sanctuary, where you will have the option to deposit all of those items into your stashes. of Anima (this caps out at 35K Anima).
First off, Anima drops come in three flavors in Shadowlands: Uncommon, Rare, and Epic. Uncommon Anima items give 5 Anima, 35 rare, and 250 epic. As enticing as epic quality Anima items are, they are also the hardest to farm. They'll likely have a chance to drop in high-end Mythic tier content later on, but right now lower and lower tier Mythic only drop rare items. So the only reliable source of Epic Anima items at the moment is the small number of quests that reward them.
This means that if you plan on farming Anima in Shadowlands, you'll want to pick up uncommon and rare Anima items. These are much easier to acquire than the Epic Anima drops, especially if you don't mind some exploring. World quests can reward 1-4 rare anima items, and dungeon bosses sometimes drop a rare quality item or two. Sometimes you kill a mob and a quest will get you a rare Anima item on handover, so there's little harm in killing regular mobs.
Also, be sure to grab your Daily Calls: those reward chests contain Anima items, and those quests tend to require completing the World Quest. There are also quests that award multiple Rare Anima items upon completion, such as the weekly dungeon quests in Oribos that also reward Covenant faction reputation. Keep an eye out for these quests and be sure to clear them. Additionally, Daily Dungeon and PvP Finder queues offer up to one rare item for each available option (except Arena).
Shadowlands chests will always contain a handful of uncommon Anima items (although map-marked chests tend to contain more than standard chests). Usually these add up to match the anima of a single rare item, so chests are well worth looting if you come across them. Otherwise, if you want to max out your Anima farm, you'll want to at least clear the marked chests from the map.
Rare mobs also drop uncommon Anima items, so if you come across one in the wild, it's worth killing it. Granted, at our current item level, you'll want a party to help you take down most of these enemies, so set a pin on your map and share the location in the general chat. Since rare mobs tend to drop pets and mounts in Shadowlands, players will flock to your location. That, and they probably grow Anima as well.
What is Anima for in Shadowlands?
Anima has several uses in Shadowlands. One of your weekly Renown quests will require you to farm 1000 Anima to complete, and any Anima items you have on hand before grabbing this quest will not count. It's not a hard number to hit, even with the occasional squeak, assuming you've at least completed your daily calls and completed some world quests that reward Anima. Outside of this quest, Anima has little effect on your progress.
Anima is also used to purchase Sanctum upgrades (the Teleport Network, Anima Conductor, Adventure Table, and Sanctum Feature), cosmetics and the like from the Renown Vendor, to power up the Anima Leader, and to send companions on missions to the adventure board. Sanctum upgrades should be your first priority when it comes to farming Anima, but they also require Redeemed Souls which are locked behind a weekly quest.
Stock up on what you need for your next weekly Sanctum upgrade, then farm some more to make the following weeks easier, have a cushion for later cosmetic purchases, or take a break. You can technically farm Anima from your Adventure table, but the cost/reward ratio isn't the best. It's an option, but you'll want to upgrade your companions for Soul Ash missions that appear at higher levels.