Seastars with high AC - 5e idea?

[Cleon]

good points - Id say immunity to blind, charm, deafening sums it up

Updating the Giant Brittle Star (Ophiuroid).

After thinking it over I viewed WIS 9 with more acceptance. Starfish are among the "smarter" Echinoderms (or should that be "wiser"?) so it feels OK giving it the same Wisdom as a Black Pud, which are among the more sophisticated oozes.

Let's see, the current Armor Class 15 is fine (I'm thinking the Sea Star might be a point higher when we get to it, as they're a bit sturdier of build).

So what's next in the block… Skills?

Hmm, should it even have skills? Well, I guess the current Stealth proficiency is OK. It's not exactly smart, but neither are Giant Crabs and they have Stealth. Then again, some real world Brittle Stars are quite brightly coloured and stand out from their surroundings. Those animals aren't exactly camouflaged (although it presumable depends on background - a black brittle star on pale dead coral stands out like a sore thumb, but if it were crawling over a dark lava rock it'd be hard to spot).

Heck, it needs some way to get close enough to prey to catch them, so it might as well have Stealth.

It should be Skills Stealth +3 though from DEX 9 and a +2 prof bonus, or possibly Stealth +5 if we want do give it double proficiency. That'd give it the same Steath as a Giant Octopus.

Alternatively, or in addition, we could give it Underwater Camouflage like an Octopus, since they do have chromatophores, but from what I read they can only get a bit lighter or darker, they don't have the amazing camouflage abilities of a Octopus.

 

[Casimir Liber]

I think stealth is fine - they creep along steadily and slowly. Not hugely known for camouflage skills

 

[Cleon]

I think stealth is fine - they creep along steadily and slowly. Not hugely known for camouflage skills

Fine.

Do you prefer single proficiency for Stealth +3 or double for +5?

 

[Casimir Liber]

Fine.

Do you prefer single proficiency for Stealth +3 or double for +5?

Maybe just single? When I think double I think shadows and really sneaky things

 

[Cleon]

Maybe just single? When I think double I think shadows and really sneaky things

As you like, Stealth +3 it is.

Offhand I can't think of any damage vulnerabilities/resistances/immunities that seem appropriate and you don't have and in the current D&D Beyond Rough Draft so I'll cut that bit out of the Enworld Working Draft too.

Updating the Giant Brittle Star (Ophiuroid).

That just leaves senses. Apart from the default passive Perception 9 the Rough Draft has Blindsight 30 ft. and Tremorsense 30 ft.

I guess we should consider (a) does it need both of those (i.e. would blindsight alone be OK?), (b) is the range long enough, and (c) should the blinsight have the "(blind beyond this radius)" proviso or not?

Hmm, in order:

(a) Tremorsense? This sense is mostly possessed by burrowing creatures, like a Purple Worm, although there are a few 5E monsters with it that don't have burrow speeds such as the Galeb Duhr. That said, some brittle stars burrow in the sediment and reach out their arms from the silt to capture food that's floating past so tremorsense isn't out of the question. Plus they're noted for having a keen sense of touch.

Dang it, I can't decide but am leaning towards them just having Blindsight.

(b) Range? This is trickier. Some Large "mundane" monsters have tremorsense 30 ft. like the Hunter Shark, while others like an Ochre Jelly have 60 ft.

Perhaps it would help to consider how far it can feel with its arms? Which requires us knowing how long the are. Let's see, looking at some Brittle Star pictures online and scaling them up, I'd say a Brittle Star's arms average about six to eight times longer than the diameter of its disc-shaped body.

So, if we say its body is 3 feet across the arms will be about 20 feet long. That suggests we should consider blindsight 60 ft., since it it had 30 ft. it could only sense things 10 feet beyond its tentacle tips.

Which reminds me, since Brittle Stars have such long flexible arms they ought to have increased Reach with their arm attacks.

(c) Blind Beyond? Hmm, I'm not sure how effective their array of eyespots is at sensing creatures. I suspect it's fairly rudimentary, but it seems rather limiting to have the "(blind beyond this radius)" limitation. Perhaps we should give them some other restriction such as some kind of "rudimentary eyesight" trait. Perhaps they have Disadvantage on Wisdom (Perception) checks that rely on sight, and can only see shadowy outlines of objects and creatures?

 

[Cleon]

So, if we say its body is 3 feet across the arms will be about 20 feet long. That suggests we should consider blindsight 60 ft., since it it had 30 ft. it could only sense things 10 feet beyond its tentacle tips.

Further on that, how much would a creature that shape likely weigh? That'd confirm whether those dimensions are right for a Large beast.

A Giant Brittle Star ought to weigh about the same as a half-size (3-foot across) flattened beholder with 20-foot constrictor snakes strapped to it. There arms are comparable in shape to serpents, after all!

Let's see, if the body is a spheroid 3 foot across and 18 inches thick and its five arms are cones 20 foot long and 9 inches in diameter at the base, then its volume is:

Body = 4/3π×1½×1½×¾ = 2.25π = 7.0686 cubic feet
Arms = 5×⅓π×⅜×⅜×20 = 4.6875π = 14.726 cubic feet
Total = Body + Arms = 6.9375π = 21.795 cubic feet

Now it's going to have the same density as water like most aquatic animals, which is roughly 62.5 pounds per cubic foot.

So if the above volumetrics were accurate, it ought to weigh about 1362 pounds in total, and each arm weighs roughly 184 pounds (as they have a volume of 2.94 cubic feet apiece). That sounds about right, as a 20 foot long Reticulated Python can weigh less than that.

That's a pretty reasonable weight for a Large sized creature, since Large is roughly as big as a horse. In 3E a Large creature is usually in a range from 500 to 4,000 pounds, and 5E seems to use a similar size scale so the weights might be about the same.

Besides, it leaves room for the disc to be a bit bigger and the arms a trifle thicker or longer and still be lighter than a Rhinoceros, which is also Large.

For example, if we make the disc four feet across its volume becomes 4π instead of 2.25π, increasing the total weight to 1,706 pounds; make the 4 ft. disc two feet thick and it becomes 5⅓π and 1,967 pounds (or about a short ton). If we make the arms thicker, say a foot at the base, and that'd weigh about 327 pounds each, the weight of an big Green Anaconda.

So I can see these creatures easily weighing 1,400 to 3,000 pounds or so assuming they have discs 3 to 4 feet across and arms 20 to 25 feet long.

 

[Casimir Liber]

Dimension stats sound reasonable above

10 ft reach sounds prudent with arms

I can go with blindsight 60ft and dropping tremorsense

 

[Cleon]

Dimension stats sound reasonable above

I'll add a note to my Working Draft so we remember those details for later.

10 ft reach sounds prudent with arms

I was thinking 15 ft. like a Giant Octopus, since that has the same size and a similar "grabbing prey with long appendages" approach to combat.

Incidentally, doesn't it seem weird to you that the 5E Giant Octopus has lost the bite attack it had in all previous editions? Where did its beak disappear to!

However, I was going to leave that 'til later, when we get to the Actions section.

I can go with blindsight 60ft and dropping tremorsense

Hmm, how about we add a Variant: Burrowing Brittle Star in the Description, that has no swim speed but adds burrow 10 ft. and tremorsense 30 ft. to the standard giant brittle? It should get some kind of camouflage/concealment when buried as well. There are many real life Ophiuroids that live in silty seafloors.

A Burrowing Variant would presumably bury itself under mud or sand and wait until it feels prey moving nearby, then reach out its arms…

 

[Cleon]

I'll add a note to my Working Draft so we remember those details for later.

Updated the Giant Brittle Star (Ophiuroid).

Added notes for a Shed Arms Reaction as well as the points posted above.

Okay, we've got Special Traits to finish next.

I propose:

Rudimentary Vision. The giant brittle stat has disadvantage on Wisdom (Perception) checks that rely on sight. It perceives patterns of light and darkness and can only see the silhouette or shadow of a creature or object; it can not see colors or fine details.

Regrowth. If a giant brittle star loses an arm, organ or other body part and survives, it regrows the lost body parts as it heals. It takes # (#d# + #) days for a giant brittle star to replace a missing arm.

Oh, and we've also got Capable Clambering in the Rough Draft.

Capable Clambering. A giant brittle star ignores difficult terrain penalties due to its adept movement with its arms.​

Hmm, I don't care for the wording. That means it could easily pass through difficult terrain caused by thickets and thorns that would surely tangle up its arms.

How about:

Crawling & Clambering #1. A giant brittle star ignores difficult terrain penalties caused by slippery, smooth or sheer surfaces because of the agility and sticky grip of its arms.​

It doesn't really need the explanation - that could be mentioned in the Description.

Crawling & Clambering #2. A giant brittle star ignores difficult terrain penalties caused by slippery, smooth or sheer surfaces.

Description
Tube feet are sticky and used to hold and manipulate prey as well as cling to surfaces, even vertical cliffs or cave ceilings.​

Hell, why don't we give it a modified version of the Spider Climb trait of a Giant Spider?

Crawling & Clambering #3. A giant brittle star ignores difficult terrain penalties caused by slippery or smooth surfaces and can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Description
The tube feet are sticky and used to hold and manipulate prey or cling to wet and slippery surfaces, such as cliff faces and cave roofs.​

Do you like any of those? #3 is my favourite.​

 

[Casimir Liber]

Yes - going with #3 so looks like this now: