Stygia in Shadowlands is earned by killing enemies in the mouth and completing quests.
It is important to note that the Stygia obtained by killing enemies in the Maw area of Shadowlands varies. While you gain a Stygia from both normal and regular Elite enemies, you'd be much better off hunting down the various rare enemies that spawn in the Maw. For example, a rare special encounter (the rarest found in Maw) leaves 45 Stygies on death. There's a catch though: Killing rare enemies increases your Eye of the Jailer meter faster than assassinating regular enemies.
Technically, you can farm more Stygia and gain less Eye of the Jailer by killing regular mobs than by killing Rare Events, but that's a job and a half. Rare enemies aren't your only source of Stygia - Maw has daily and weekly quests that provide valuable currency, but these increase your Eye of the Jailer counter more than killing a rare monster! The rare ones also have a chance to drop lore quest items, which can be reputed with Ve'nari.
The key to successful and efficient Stygia farming is focus. First and foremost, you'll want to knock out your hangover quests, then fall back on rare ones and events. Prioritize minor and major rare over rare events, as they grant more Stygia per eye (the rare special encounters are the skull icons on the minimap, while all other rare are the usual star) . There is a weekly Wrath of the Jailer event that pops up occasionally, although you want a team to take down the final boss (this shouldn't be difficult to organize, but can get more difficult later in the week as you go). more and more players complete it). As a bonus, Wrath of the Jailer has a chance to drop level 183 gear.
Burningbamf on WoWHead has created a great chart that breaks down all of the sources for Stygia, which I've included below. Refer to this if you want to know exactly what you'll earn from each source and how much Eye of the Jailer will cost you. Each rank of Eye of the Jailer takes 1000 points to reach, so at 5000 points you will reach Rank 5 and no longer be able to earn Maw Stygia (stygia and reputation gains are literally disabled at Rank 5).
Stygia in Shadowlands is used to purchase items from Ve'nari, your helping hand in the Maw. She has items that will aid both the Maw and the Torghast, in addition to two items that will greatly benefit your late-game progress: the Unlimited Reality Shard and the Space Realignment Device. Remember that Stygia is abandoned when you die, but only a part of what you hold. If you want to get it back, you'll have to go back to your corpse and loot it. If you die before you get your Stygia back, it will be lost forever, and you'll drop Stygia again which can be picked up from your new corpse. Approach your Stygia farm with caution and choose your tasks wisely.
