In the Feywild, creatures spring into existence that are the manifestations of the feelings of mortals. In the Shadowfell, this happens, too, but only for the really bad feelings. These creatures are the sorrowsworn.
The intriguing thing about the sorrowsworn is that they literally feed off negative emotions. Doing violence to the Angry, for instance, makes its attacks more effective, while refusing to do violence to it reduces its effectiveness.
All sorrowsworn have 60 feet of darkvision—good for the gloom of the Shadowfell—and are resistant to physical damage from any type of weapon, not just nonmagical weapons, while out of bright light.
Lowest and weakest of the sorrowsworn are the Wretched. They live up to their name: of all their abilities, only their Dexterity is average or better. They also have lamprey mouths, which aren’t wretched per se, just disturbing as all heck.
Because of their uncompensated low Strength, the Wretched should always outnumber player characters by at least 2 to 1, preferably at least 3 to 1. For this reason, despite their low challenge rating, they really aren’t a monster to throw at beginner-level adventurers but rather should be saved for, say, level 4 to 6 (you can send them against level 2–3 PCs, but only if you want to put the fear of God into them).
Their Wretched Pack Tactics contains an interesting twist on the vanilla Pack Tactics feature: They still get advantage on attack rolls when they have an active ally adjacent to their target, but when they don’t, they have disadvantage on their attacks. It may be suboptimal for, say, a kobold or a thug to persist in a solo engagement, but for the Wretched, it’s not merely suboptimal but almost pointless—unless a Wretched has latched onto its target.
Despite their weakness, the bite of the Wretched is nasty. First, it does a d10 of damage, which is a lot for a Medium creature, let alone a Small one; second, on a successful hit, the Wretched latches on, and as long as it’s not pulled off, it automatically does another d10 of necrotic damage at the start of each of its turns.
The modus operandi of the Wretched, therefore, is to swarm. Three or more Wretched rush a target at once. They all attack with advantage, and as many of them as possible latch on. Once one is latched on, its target is especially attractive to other Wretched, not just to those attacking him or her already but also to those that have tried and failed to latch onto a more difficult target nearby. A Wretched pulled off by its target attacks and tries to latch on again on its next turn if any of its fellow Wretched have managed to latch on themselves. A latched-on Wretched detaches, however, if all the other Wretched attacking its target have been killed or moved on to other targets.
Evolutionary imperatives don’t work the same way in the Shadowfell, where many creatures manifest out of psychic energy rather than biological processes. The Wretched exist in almost infinite quantity and have nothing to live for, so whether they flee has nothing to do with how much damage they take. Rather, they flee when they no longer outnumber their targets by at least 2 to 1.
The Lost, according to Mordenkainen’s Tome of Foes, “are representations of the anxiety and fear that people experience when they can’t find their way,” and consequently this is when and why one of them appears. A single Lost is an appropriate challenge for a party of mid-level adventurers; multiple Lost are better saved for PCs of level 11 and up.
The Lost are multi-armed brutes, with very high Strength and Constitution; their Dexterity isn’t too shabby, either. And they have proficiency in Athletics, reflecting their predilection for grappling.
The Lost’s arms are tipped with spikes rather than fingers, and they can attack with these twice per turn. But their preferred attack action is Embrace, which does approximately as much damage as their Multiattack plus a grapple that inflicts ongoing psychic damage on the target’s turn if the grapple isn’t broken. Not only that, if a Lost takes damage while grappling a target—either from that target or from an ally of the target—it punishes the target with even more psychic damage.
Unlike many grappling monsters, the Lost aren’t limited when grappling a creature to attacking that particular creature, although they can grapple only one creature at a time. They also don’t need to actively attack their grappled targets to continue to inflict damage upon them. Thus, a Lost’s first goal is to Embrace a target; once a target is Embraced, it uses its Multiattack to fend off those who’d rally to its target’s defense.
The Lost could attack anyone in a party, but it chooses whoever is most distressed by the party’s disorientation. It doesn’t flee, no matter how much damage it takes. And depending on how much you want to ratchet up the horror, you can decide that the Lost doesn’t let go of its Embraced target even after that target falls unconscious—instead continuing to hold on until the target is dead. It would be in character.
The Lonely is a boss monster for mid-level parties and a significant nuisance even for high-level adventurers. It zeroes in on emotional isolation, on PCs (or NPCs) who feel alienated from their companions. Alienation isn’t the same thing as solitude, though: the Lonely is optimized not for stalking solo targets but for picking one or two targets out of a group.
To initiate combat, the Lonely must approach within 60 feet of its prey—really, 30 feet, if it’s going to be at all effective—as well as its prey’s companions, since it has disadvantage on its attacks if it’s not within 30 feet of at least two other creatures. Without proficiency in Stealth, it’s not likely to get the jump on a party of PCs in dim light, even with disadvantage imposed on Perception checks (which PCs with darkvision won’t have anyway), so the Lonely prefers to attack in full darkness.
The Lonely’s combat script is dictated by its rigid Multiattack: one Harpoon Arm and one Sorrowful Embrace. Harpoon Arm does piercing damage and grapples; Sorrowful Embrace reels the target in and does psychic damage. The passive feature Psychic Leech continues to do psychic damage to grappled targets, even as the Lonely attacks other creatures.
However, once the Lonely has gotten the target(s) it came for, it has no reason to stick around; instead, it tries to walk off with them so that it can leech the life out of them in peace. It uses the Dash action as long as creatures other than its target(s) aren’t attacking it, although because it’s slowed by half, it can cover only 30 feet in its turn. If it’s attacked while trying to leave, it uses the Dodge action instead. It doesn’t let go of its targets as long as it’s alive, and if one struggles free, it mechanistically tries to grapple that target again. It never defends itself per se, though it drops its prey and retreats while Dodging if seriously wounded (reduced to 44 hp or fewer). But like the Lost, as long as it’s got prey in its clutches, it keeps on leeching the life from its target(s) till there’s none left.
The Hungry isn’t one you’ll run across too often, because PCs do usually have the presence of mind to feed themselves, but if they’re botching their Survival rolls while foraging in the Shadowfell, it might show up. It’s a ferocious brute that you should throw at high-level adventurers only; mid-level adventurers can handle one only when fully rested, which is exactly the kind of time the Hungry won’t show up.
The Hungry, an extraordinarily strong brute, pounces on the most famished person in the party (“pounces” may not be the right word, since the Hungry has nothing in the way of stealth; “lunges at” may be better) and Multiattacks with its bite and claws. The bite is a vanilla attack doing piercing and necrotic damage; the claws, on the other hand, not only do damage but also grapple and restrain the target, setting the Hungry up to bite with advantage on its next turn. It keeps chowing down until the target is dead—not just unconscious, but dead, i.e., devoured.
And that’s all it does—it doesn’t have the Intelligence to deviate from the script. If a target gets free, it chases that target down. Once it’s finished off a target, it moves on to the next one, until it’s eaten the whole party. It retreats by Dashing when seriously wounded (reduced to 90 hp or fewer).
The Angry is the most dangerous of the sorrowsworn, and the only one with enough Intelligence to adapt to a changing situation, but it’s still not especially sophisticated. Yet another brute, it charges directly into the fray, homing in on angry characters. This is one of the few creatures in the Dungeons and Dragons multiverse that wants to fight a high-level barbarian. In fact, because its Rising Anger feature imposes disadvantage on attack rolls after any round in which it hasn’t taken damage, it wants to bait out attacks from those most likely to hit it. (If it were smarter, it might try to bait out attacks from those likely to hit it but not likely to do a lot of damage to it. But it’s not.)
Its Multiattack consists solely of two hook-hand attacks. It has no other attacks, so it just does this over and over again. But it does change targets, if and only if it becomes apparent that another enemy is hitting it more often, or with “angrier” attacks. What do I mean by an “angry” attack? Well, barbarian Rage, of course, but also a paladin smite spell, or a ranger with the Colossus Slayer feature, or a spell cast by a War domain cleric, or a 3rd-level-or-higher evocation spell—stuff like that. A moonbeam spell cast by a hippie-dippy druid wouldn’t qualify, nor would a weapon attack that did piercing damage when someone else was bludgeoning or slashing.
An Angry will fight as long as its enemies keep fighting. But if its enemies refuse to fight it—if they go a whole turn not only without hitting it but without even trying to attack it—it roars, stamps its feet and makes “Come at me, bro” gestures. If they go without attacking for two whole turns, it makes a huffy noise and stalks off.