Star spawn are new arrivals in the Dungeons and Dragons universe. The name seems to be borrowed from H.P. Lovecraft’s Cthulhu mythos, but according to the Powers That Be, star spawn aren’t native to the Far Realm specifically. Some of them are from the Far Realm, but others are associated with “Elder Evils” that inhabit other planes, such as the Shadowfell, the Gray Waste and the Abyss. They understand and speak Deep Speech, which is not the same as Undercommon, but rather a language associated with the Far Realm; it’s also spoken by neogi, mind flayers, beholders and aboleths.
There’s a variety of star spawn for every level of play, from the lowly grue to the boss-level larva mage.
The star spawn grue is a weak skirmisher. Its extremely low Strength is an indication that it will never be encountered alone, but rather with many others of its kind. If your run-of-the-mill high fantasy campaign opens with a scuffle between the player characters and a patrol of goblins or kobolds, or your horror campaign begins with skeletons or zombies, your “maw of madness” campaign can open with a swarm of grues.
Star spawn grues come out at night (60 feet of darkvision) or dwell in subterranean pits. They have only two special features, one active and one passive, but one reinforces the other. Aura of Madness imposes disadvantage on saving throws against creatures within 20 feet, as well as attacks against non-grues. It seems odd that a creature should impose disadvantage on attacks against beings other than itself, but this makes grues useful auxiliaries to more powerful star spawn. It also renders enemies within range more vulnerable to the grue’s Confounding Bite, which in addition to doing vicious piercing damage (two dice, rather than the usual one) also requires the target to make a Wisdom saving throw, or else other attacks against him or her will have advantage for a round.
Star spawn are aberrations, but this doesn’t mean they’re not evolved creatures; they simply evolved under different conditions. Their Wisdom is more than high enough for them to have a self-preservation instinct, which means a star spawn grue will retreat when seriously wounded (reduced to 6 hp or fewer). But rather than Dodge or Dash, a grue engaged with only one melee opponent will simply use its full movement to move away (potentially incurring an opportunity attack), then Ready a Confounding Bite against any enemy who pursues; while a grue engaged with more than one melee opponent will instinctively Disengage before moving away.
For the middle-grade adventurer, we have the star spawn mangler, also a low-Strength skirmisher that never attacks alone. The mangler has proficiency on Dexterity and Constitution saving throws, two of the big three; that leaves Wisdom, which means that manglers will aggressively home in on bards, illusionists and any other enemy casting mental manipulation spells as soon as this ability becomes apparent and try to take them out of the fight ASAP.
Manglers are quick and can also climb, so they’ll turn a fight into a three-dimensional affair if they can. They’re ambush predators whose Shadow Stealth feature allows them to keep ambushing their targets as long as they have a dark corner to slip into. Combine this with the insane Flurry of Claws action, with allows six claw attacks plus an additional turn’s worth of movement without provoking an opportunity attack at either end of the movement, and you can see where the mangler gets its name from. This is especially true in the first round of combat, when the Ambush feature grants it advantage on every attack it makes against an enemy who hasn’t taken a turn yet, not just on the first one (which is all you get from being an unseen attacker—once you attack, you’re no longer unseen). And since the mangler’s claw attack does bonus psychic damage when it has advantage on its attack roll, this means that if all its attacks hit, it can do an average of 93 points of damage in a single combat turn, and a maximum of 144 points of damage.
Flurry of Claws requires a recharge roll, but it’s a generous one: it recharges not on the usual roll of 5–6 but on a roll of 4–6. That means that, on average, a star spawn mangler can use this attack action every other turn, which is still better than using its un-recharged claw-claw Multiattack every turn (six attacks over two rounds, rather than four, plus the free movement).
So a pack of manglers are going to start combat from a place of hiding. They may have grues with them, but under no circumstances will the grues lead the attack, because the manglers must strike first, with surprise if possible. Ambush grants them advantage on every attack roll, and they use Flurry of Claws to exploit this benefit to the fullest. Then they immediately move to the nearest shadow and, with Shadow Stealth, use their bonus action to Hide again (with Stealth proficiency!). The next time they attack, Ambush no longer benefits them, but they’ll still benefit from unseen attacker advantage on the first strike.
Now here’s where we get into a fiddly mechanic about how recharge works. You roll for recharge at the start of each of a creature’s turns, not at the moment it tries to use the action. So before the mangler does anything, you already know whether it has Flurry available to it or not—and in a sense, so does it. Thus, if Flurry happens not to recharge, the mangler remains in hiding for a turn. If it does recharge, it springs out and Flurries again.
Flurry of Claws is better than Multiattack as long as a mangler gets to use it at least once out of every three turns. Thus, suppose a mangler flubs three recharge rolls, three turns in a row. At that point, it springs out and attacks anyway, using Multiattack, because otherwise it will fall behind on its damage. In that instance, it has to remain out in the open, because it doesn’t get to Hide as a bonus action. But with 71 hp, it can take a couple of hits as it waits for Flurry to recharge.
The mangler retreats when seriously wounded (reduced to 28 hp or fewer), but it doesn’t necessarily retreat right away. Rather, it retreats the first time it gets to use Hide as a bonus action as part of Flurry of Claws. Then it just doesn’t come back out of hiding.
For the mid-to-upper level range, we have the star spawn hulk, which as its name suggests isn’t a skirmisher but a brute. This one’s saving throw proficiencies are on Dexterity and Wisdom, but it hardly needs proficiency on Constitution saving throws, since it’s already got +5 to those from its natural toughness. Nonmagical weapons do only half damage against it. It’s a tank.
The hulk’s most distinctive feature is Reaping Arms, an action that allows it to attack every enemy within 10 feet of it, potentially knocking them prone. Thus, the hulk not only rushes straight into melee as other brutes do but also has an incentive to wade right into the midst of its opponents. Most creatures, even brutes, try to avoid melee engagement with multiple enemies at once. The star spawn hulk actually digs it. The only time it will refrain from using Reaping Arms (assuming it’s not on cooldown) is when it can’t reach at least two enemies. If it can move to a point where it can reach three or more, it will, even if this would incur one or more opportunity attacks.
When Reaping Arms isn’t available, it uses its double-slam Multiattack. It can divide this between two opponents, but if it uses both attacks against one, it does extra psychic damage, with potential to stun. This is a strong incentive for it to focus its attacks against a single enemy, and with its above-average Wisdom, it has a decent intuitive sense of which of its enemies is the most desirable target for that.
What makes a target desirable? The ability to do harm back to the hulk, which, most straightforwardly, probably means a magic weapon—although it may also mean spell attacks, if the hulk can get at the attacker. Since the star spawn hulk is a creature of melee—and not a very bright or flexible one—it’s going to choose a target it can reach without moving over one it has to charge to get at. But if a ranged attacker gets its attention in a way that its melee opponent(s) can’t, then it will go after that attacker. ETA: If multiple star spawn hulks are fighting together, a target knocked prone by one hulk is also a highly desirable target for any other.
A star spawn hulk does retreat when seriously wounded (reduced to 54 hp or fewer), but grudgingly, continuing to attack with Reaping Arms (if it’s recharged) or Multiattack (if it’s not) as it backs away, taking advantage of those attacks’ debilitating effects to avoid opportunity strikes.
This is already getting long, so I’ll finish up with the star spawn seer and star spawn larva mage in another post.