Thanks to DM logic, the characters in our epic-level campagin started layering spell over spell until we ended up creating a black hole. Don't ask how. These things tend to happen in our campaign.

As we were figuring out how to deal with the singularity we just created, one of the players asked about Black Balls/Umbral Blots, and how they would fare against a black hole, what with both of them tending to be unstoppable matter devourers, so which would win in a fight?

I apologize if this comes out as confusing, because I'm not even sure if I'm asking the proper question either.

  • \$\begingroup\$ What 'house rules' are you using for a Black Hole? \$\endgroup\$ – Ruut Oct 25 '15 at 5:04
  • \$\begingroup\$ Black Holes (IRL): Material in the immediate vicinity of a black hole undergoes extreme compression and superheating. The result is a quasar, which emits so much energy as visible light, that it can outshine the galaxy in which it is located by many thousands of times. \$\endgroup\$ – Ruut Oct 25 '15 at 5:06
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    \$\begingroup\$ This feels a little Gorilla v Shark-y to me, but I think it's ok, since 1) it's a real situation 2) it has a clear answer \$\endgroup\$ – Please stop being evil Oct 25 '15 at 5:59
  • \$\begingroup\$ Similar 3.5 only question about colliding spheres of annihilation. \$\endgroup\$ – Hey I Can Chan Oct 25 '15 at 10:09
  • \$\begingroup\$ I'm amazed that 3.5e has enough rules on umbral blots and black holes that this question can be sensibly answered. For a given definition of "sensibly." \$\endgroup\$ – GMJoe Oct 26 '15 at 3:08

Fluff+Some Crunch Answer

The Epic Level Handbook has two relevant things to say about the umbral blot:

A hovering sphere of absolute void, an umbral blot (sometimes called a blackball) is an extraordinarily dangerous opponent to any who come into contact with it.

An umbral blot is an odd anomaly that's actually kinda the reverse of a black hole. Instead of tons and tons of matter densely packed into a small volume, the umbral blot is no matter, somehow taking up space. The fact that it's an absolute void would mean that it has almost no interaction with a black hole. You need mass or energy to be affected by gravity, and an umbral blot, having absolutely nothing in it, would simply not interact (as far as I can tell).

The other important thing that the Epic Level Handbook lists is the Disintegrating Touch ability:

Disintegrating Touch (Ex): Any material object that comes into contact with a blackball is immediately disintegrated unless it succeeds at a Fortitude save (DC 38). A character or object that has been disintegrated by an umbral blot disappears completely, leaving behind not even dust to mark its passing.

Unlike umbral blots, black holes are actually made of something. They have mass and matter, and would be objects. If an umbral blot makes its way towards a black hole, it wouldn't care about its gravity, and if it ran through a black hole, the umbral blot would win. Complete and utter disintegration for the black hole, not even leaving any traces behind. The umbral blot has greater teleport at-will, so if it decides to, it might just teleport right into the black hole and eat it for the fun of it.

I'd imagine the result of the sudden loss of gravitational pull on things orbiting the black hole would be quite interesting.

Alternative Answer

The umbral blot is still, somehow, a creature. If you're a strong enough grappler, you can even grab it and wrestle it into submission. Don't ask me how, it just works. If the rules you're using for black holes has rules for interacting with creatures, it would be affected as normal, regardless of how it actually should work based on its composition.

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  • \$\begingroup\$ If you want to take sort-of-RL physics into account, I think the gravitational shockwave from the black hole's disappearance would destroy the universe. :-) \$\endgroup\$ – Harry Johnston Oct 25 '15 at 7:45
  • \$\begingroup\$ @HarryJohnston Fortunately, I think we are safe from that in even the most liberal interpretation of published D&D settings, since they all subscribe to a cosmology that is separated by more than time and space thanks to the hard-written presence of spells like gate. The Prime Material Plane would be destroyed, for example, but the gods would collectively shrug their shoulders on the other Planes -- depending on their investment into the mortal races. Hey I Can Chan's quotation seems to support this. \$\endgroup\$ – Lucas Leblanc Oct 26 '15 at 20:54

First, you need a black hole…

Luckily, Dungeons and Dragons 3.5 has your back. Elder Evils in the EL 20-21 encounter "The Obelisk" describes a caster who, under unusual circumstances, combines a sphere of annihilation with a well of many worlds. Five rounds after he does the

sphere becomes a "black hole," annihilating everything in existence. If abandoned, it picks up speed and power, drawing the island, the waters, the air and everything else on the Material Plane into its dimensional fissure, erasing all existence in 1d12+6 minutes. (142)

The real fun begins on the next page's Features of the Area under Sphere of Annihilation:

Once the ["black hole" is created], the resulting tear pulls air, fine creatures, and debris toward it. After the first minute, the effect intensifies, and all characters must succeed on DC 15 Balance checks. A failed check means the character falls prone. A check failed by 5 or more indicates the character falls prone and slides 1d2×5 feet toward the sphere. Each minute thereafter, the Balance DC increases by 5. After 3 minutes, flying anywhere within 100 feet is impossible, and such characters are automatically sucked into the sphere unless they succeed on a Reflex save against the Balance check DC. (143)

Yes, resisting the black hole's pull requires increasingly difficult Balance skill checks. No one's laughing at the thief-acrobat now, are they?

Apparently, there's no range at which a creature doesn't make these Balance skill checks. Every creature on the Material Plane makes a Balance skill check, falls prone if it fails, and slides toward the black hole if it fails by 5 or more. Which is hilarious.

(I think, in the initial description, the author assumes the destruction of the Material Plane (and, by extension, all creatures thereon) because even level 21 characters will struggle to succeed on the, like, DC 100 Balance skill checks needed to resist the black hole's pull, but players are infinitely resourceful, so I wouldn't put it past them to survive beyond the given 18 minutes, especially if they manage to employ a greater teleport, which has "no range limit.")

While the Elder Evils black hole is inside quotation marks—likely indicating it's not a real hard-science astronomical feature but a fantasy black hole—, unless you want actual science in a fantasy game (brr), these rules seem a playable enough.

…And that may (or may not) mean a doomed umbral blot

Thus, in the abstract, an umbral blot (EL 223-4) will be no match for this ersatz black hole. While the umbral blot has a Balance skill check bonus of +10 due to its Dexterity, it will eventually hit the sphere, and the umbral blot will be destroyed. Although described as a "hovering sphere of absolute void," the umbral blot is ultimately merely another construct, therefore vulnerable to a sphere of annihilation.

This shouldn't happen to the umbral blot, though. The creature can use both greater teleport and plane shift as extraordinary abilities at will. But, were it somehow convinced to travel within 100 ft. of the black hole, the umbral blot will be consumed like anything else. The umbral blot's greatest weakness? It has only a fly speed and flying creatures "are automatically sucked into the sphere unless they succeed on a Reflex save against the Balance check DC." Who knew that would doom a creature with a challenge rating of 32?

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    \$\begingroup\$ So I heard you like black holes. In d20 Future you can fly a black-hole powered spaceship near a black hole and throw black hole grenades at it. \$\endgroup\$ – Hey I Can Chan Oct 25 '15 at 12:05
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    \$\begingroup\$ Taking that encounter description literally, wouldn't the presence of at least one rod of cancellation anywhere on the Material Plane be enough to save it from total annihilation? Of course, the immediate surroundings (for perhaps rather broad values of "immediate", depending on how close the nearest rod happens to be) of the sphere would still get rather thoroughly messed up, but at least the "erasing [of] all existence" should be averted. \$\endgroup\$ – Ilmari Karonen Oct 25 '15 at 12:26
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    \$\begingroup\$ @IlmariKaronen I assume a creature must touch the rod to the sphere, taking an action. That is, since smacking something with the rod is usually an action, smacking a sphere should be, too. But, you're right, it's ultimately up to the DM if mere possession of a rod of cancellation when it contacts a sphere of annihilation counts as "a rod of cancellation touch[ing] a sphere of annihilation, ...negat[ing] each other in a tremendous explosion." \$\endgroup\$ – Hey I Can Chan Oct 25 '15 at 12:38
  • \$\begingroup\$ It is questionable if the rod must be used to "cancel" an item. Problem, usually, is that rod won't go and touch something all by itself. But if something is pulling it in contact, then the problem is solved. \$\endgroup\$ – annoying imp Oct 25 '15 at 14:46
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    \$\begingroup\$ I encourage anyone really interested in the mechanics of the rod of cancellation to pose a new question about the item. I included information on how to stop the ersatz black hole because I thought it was useful, interesting, and fun, not to court controversy (and, in fact, did so without knowing there was any). \$\endgroup\$ – Hey I Can Chan Oct 25 '15 at 16:29

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