Now that the holiday madness is over, it’s time to get back down to business, and the business of the day is the astral dreadnought, whose name tells you most of what you need to know: This fearless titan drifts through the astral plane, obliterating everyone and everything it comes across.
While its Strength and Constitution are epic, its Dexterity is dismal—a gargantuan beast like this doesn’t turn on a dime. Nor does it possess Intelligence beyond animal level. Its Wisdom is high, however, and its Charisma is exceptional—perhaps reflective of its ability to command awe. Despite its extremes, this is a straightforward brute ability contour, indicating a creature whose approach is to close in and maul.
Its resistances and immunities aren’t all that relevant, because (contra the flavor text in Mordenkainen’s Tome of Foes) its Intelligence is so low, it’s not going to bother to distinguish between one target and another. However, its relatively high Wisdom indicates a prudent, instinctual self-preservation impulse. The astral dreadnought is a creature so unaccustomed to resistance that any prey that can inflict a moderate wound against it (reduce it to 207 hp or fewer—yeah, that number’s not a typo) will give it pause.
That’s not fear, mind you; that’s just surprise. By itself, it’s not enough to make the astral dreadnought retreat. Rather, it triggers an intuitive assessment of the situation, represented by the encounter difficulty measure in the Dungeon Master’s Guide (chapter 3). If the astral dreadnought constitutes a Deadly encounter for its opponents, it pushes obstinately on. If it’s a Hard encounter, it backs off once seriously wounded (reduced to 118 hp or fewer); more on that later. If it’s a Medium or Easy encounter, it backs off immediately. (Yes, it’s possible for an astral dreadnought to constitute an Easy encounter. It takes a party of at least six characters of level 15 or higher.)
Running an astral dreadnought is a somewhat mechanistic affair, because its Intelligence is so low and because so many of its traits are passive (Astral Entity, Demiplanar Dungeon, Magic Weapons, Sever Silver Cord—I call this one passive because cutting the silver cord is such a jerk move, there’s no reason not to do it). The only decisions you need to make as a dungeon master are which way to aim its Antimagic Cone, whom to target with its melee attacks, and when to use its Legendary Resistance and each of its legendary actions.
The Antimagic Cone is interesting—and a bit of a Catch-22 for the astral dreadnought. Its area of effect, a 150-foot cone, is humongous. But like all conical AoE effects, it’s limited to a 53-degree arc. At great distances, this is all-encompassing, but once you get in close, it’s easy to run rings around. That’s the thing about a conical AoE: At a range of 100 feet, it covers a 100-foot swath, but at 10 feet away, it extends only 10 feet side to side. Thus, while the astral dreadnought can use its Antimagic Cone to shut down spellcasters from a great distance, it can’t do anything else to them until they get closer—at which point they can fan out, making it harder for the astral dreadnought to shut them all down.
But Antimagic Cone isn’t just for shutting down spellcasters. The effect suppresses the properties and powers of magic items, too, including magic weapons. And since it has resistance to physical damage from nonmagical attacks, it has a good reason to include magic weapons among the types of magic it wants to shut down. Which means it also has some tough choices to make once its foes rush in and encircle it—and not a lot of cognitive candlepower to expend on making those choices. Whatever it decides, it decides by instinct.
Really, there are only two criteria simple enough to apply: either it aims its Antimagic Cone at the greatest possible number of enemy creatures, period, or it aims it at the greatest possible number of enemy creatures who are doing magic things. Does it possess any kind of sense that suggests that it can detect magical energy? Not that I see. So I think it simply has to do a raw count, making this one of the astral dreadnought’s few weaknesses. However, I think it’s fair to let the astral dreadnought count from farthest to nearest, because in the event of a tie, it seems silly for it not to aim the Antimagic Cone at foes who might plink it with magic arrows or ranged spell attacks. The ultimate power of Antimagic Cone, in the case of the astral dreadnought, is that it forces hostile creatures to come closer if they want to try to hurt it.
That being said, nowhere is it written that the astral dreadnought has to stand still. It aims its Antimagic Cone at the start of its turn, before it gets a chance to move, but since astral propulsion is a matter of will rather than physics, it can move any direction it likes, not just forward. And being Gargantuan, and having a speed of 80 feet, it can barge backward up to 40 feet through any number of foes in order to bring its Antimagic Cone to bear on them. It can also move vertically and reorient itself so that it’s aiming its Antimagic Cone downward or upward, turning that cone into a circle or an ellipse as it crosses its enemies’ plane.
That being said, however, it’s a brute melee attacker first and foremost. Maximizing the effect of its Antimagic Cone is not its end goal. Its end goal is eating people, and for that, it needs its opponents close.
ETA: I occasionally get into arguments with commenters over the topic of facing, which in 5E is optional (not, as some seem to think, nonexistent). Given that the astral dreadnought’s eye and mouth are on the same side of its head, I have a strong sense that it should be able to Bite only in the same direction that its eye (i.e., its Antimagic Cone) is pointing. That doesn’t constrain whom it’s able to attack—it’s very mobile—so much as it constrains its positioning before it attacks. And, as a side note, with its high Armor Class and resistance to physical damage from nonmagical weapons, I don’t believe it pays any particular mind to the possibility of opportunity attacks.
The next question is whom to target with melee attacks, and that’s easy: whoever’s hurting it the most, and if nobody’s hurting it, then whoever seems weakest, because that’s what predators do. If these seem contradictory (why wouldn’t it attack whoever seems strongest?), look at it this way: It wants to eat people. Weaker people are easier to eat, and it can eat them faster, with less hassle. But if its eating is being interrupted by Angus MacBash and his +2 claymore, well, that’s a matter that has to be taken care of so that it can get back to the eating.
One distinction the astral dreadnought does make among its opponents is whether it’s attacking them to eat or attacking them to remove a hindrance to eating. If it’s simply removing a hindrance, it doesn’t need to get closer than 20 feet to them in order to attack with its claws. If it’s eating, then it wants to be no more than 10 feet away, so that it can finish its Multiattack with Bite. (I was uncertain whether it was possible for the astral dreadnought to use Claw twice, as part of its Multiattack, if it weren’t near enough to any target to use Bite. Jeremy Crawford was kind enough to answer my question: “A monster can use its Multiattack even if one or more of its attacks have no chance of hitting.”)
However, this is the opposite of what its opponents are trying to do: the targets of Bite attacks will generally want to get as far away as possible, while those who are managing to hurt the astral dreadnought will want to keep doing it, which means staying within their own weapons’ reach. Take the above, then, as a guide to how the astral dreadnought uses its opportunity attacks. If a prey-snack tries to move away, it Bites as soon as they start to move more than 10 feet away. If a serious combatant starts to move away, however, it waits until they get more than 20 feet away, then uses Claw to make its opportunity attack—or maybe doesn’t even bother.
The astral dreadnought’s Multiattack order is always Claw/Claw/Bite unless the first Claw attack reduces a target to 34 hp or fewer, in which case it Bites that target immediately afterward, or an incapacitated opponent is within reach of its Bite, in which case it Bites that target first, then uses its Claws. If appropriate targets aren’t within reach, it first moves to pursue its most effective attacker—or, if there is none, its most desirable prey.
An astral dreadnought’s saving throw modifiers are fairly strong, but it does have its weak points: Intelligence most of all, but also Charisma and Dexterity. Intelligence saving throws are typically efforts to see through illusions; these aren’t do-or-die rolls. Dexterity saves are for dodging damaging effects, but the astral dreadnought has a lot of hit points. Charisma saves—well, there are two things that account for about 80 percent of these, bane and banishment, and Astral Entity prevents it from being banished. Plus, it’s not strategic—it’s a creature of instinct. So I’m inclined to conclude that it uses its Legendary Resistance reflexively, every time it fails any type of saving throw, until it has no uses left.
The astral dreadnought has three legendary actions: Claw, Donjon Visit and Psychic Projection. Donjon Visit costs 2 legendary actions, and Psychic Projection costs 3. It stands to reason that the bar to clear for Donjon Visit should be high, and for Psychic Projection, very high.
Let’s look at Psychic Projection first. “Each creature within 60 feet”—so this is essentially a spherical area of effect with a 70-foot radius (since it emanates from the perimeter of the astral dreadnought’s occupied space, not from its center). Per the good ol’ Targets in Area of Effect table (Dungeon Master’s Guide, chapter 8), this would indicate 14 targets. Well, that’s too high a bar to clear. Let it suffice to say that it uses Psychic Projection as soon as it has all three of its legendary actions available and all its opponents are within 60 feet of it.
Even that criterion seems awfully steep, doesn’t it? Well, yeah. Psychic Projection consumes all three legendary actions. Extreme cost demands extreme justification. But all right, I’m a softie: Let’s say that it also uses this legendary action, if it can, as a reaction to being moderately wounded (as mentioned above, reduced to 207 hp or fewer) when at least two-thirds of its opponents are within range, and again as a reaction to being seriously wounded.
Donjon Visit is ideally suited for removing a bothersome belligerent from play—let’s say, any foe within range who successfully deals the astral dreadnought 30 damage or more in a single turn. Because this effect is only temporary, lasting a round at most, I’m not going to be a softie and give it an easier criterion to meet. Two legendary actions is a high price to pay.
When to use Claw is easy: You hurt the astral dreadnought, it hurts you back. This legendary action is strictly retaliatory, used against foes who deal more than 0 damage but less than 30, or when the astral dreadnought doesn’t have 2 legendary actions to spend.
That leaves the question of how the astral dreadnought retreats if and when it must. Because it’s so fast (I’m counting only its flying speed here—why does a creature bound to the astral plane even have a non-flying speed?) and will always be outnumbered, its best option is to Disengage. But is it smart enough to know how to do that, even instinctively? I think not. The next-best choice, because of its high Armor Class, is Dodge; therefore, that’s what it does as it retreats.
Next: TBD. I may go back and mop up monsters I’ve missed from Volo’s Guide to Monsters and Mordenkainen’s, or I may crack open Eberron: Rising From the Last War, or I may address a pair of omissions from both the blog and the book: the scout and the spy. We’ll see what kind of mood I’m in next week.