D&D 5E Beholder hunting: nasty counter-tactics to Darkness?

[FormerlyHemlock]

Hemlock seems to be using "the beholder rolls 3 eye rays, then chooses what/when/where to blast with them". Much better for utility concerns and combat, but still way below being able to choose the eyes to fire.

Yes. I don't see how you could read the MM any other way.

 

[FormerlyHemlock]

Actually it's in between. Three rays fire during the action giving a 30% chance. Then there are 3 independent legendary actions each with a 10% chance, but they are not additive with the 30%. You have to use combinatorics. The answer is going to be slightly above 30%, not 60%

Check your math. It's 60% on average, not 30%-ish. Doesn't matter if you draw with or without replacement. Either way, you'll average 360 disintegrations per hour.

 

[Celtavian]

So would the beholder get Legendary Action eye rays if it wasn't fighting other creatures? Legendary Actions only occur at the end of another creature's turn by RAW. If not fighting creatures, it would only get 3 eye rays a round in non-combat situations by RAW? Would it be able to use Lair Actions if not in combat and no initiative was rolled? I'm just not sure by RAW it can.

If it can't use Legendary Actions or lair actions out of combat by RAW, then it's three eye rays a round with a 10% chance of rolling disintegrate over the course of 600 rounds in an hour. Wouldn't that be closer to 60 disintegrates an hour? That would be 60 10 foot cubes disintegrated an hour. The beholder could do 600 cubic feet of tunneling per hour using random eye ray rolls.

We are talking about running things by RAW, right? We're unconcerned with how little sense it makes, right?

 

[FormerlyHemlock]

So would the beholder get Legendary Action eye rays if it wasn't fighting other creatures? Legendary Actions only occur at the end of another creature's turn by RAW. If not fighting creatures, it would only get 3 eye rays a round in non-combat situations by RAW? Would it be able to use Lair Actions if not in combat and no initiative was rolled? I'm just not sure by RAW it can.

Fair enough. In that case it can't Disintegrate anything at all except in combat. Obviously I wouldn't enforce that rule but you could if you liked.

 

[Dausuul]

If it can't use Legendary Actions or lair actions out of combat by RAW, then it's three eye rays a round with a 10% chance of rolling disintegrate over the course of 600 rounds in an hour. Wouldn't that be closer to 60 disintegrates an hour? That would be 60 10 foot cubes disintegrated an hour. The beholder could do 600 cubic feet of tunneling per hour using random eye ray rolls.

You're off by a factor of 300, due to two mistakes:

• The beholder makes three rolls for its eye rays each round, and re-rolls duplicates. Therefore, it has a 30% chance per round to roll disintegrate.
• A 10-foot cube is 1,000 cubic feet.

So, the beholder can disintegrate 180,000 cubic feet per hour; or, if you prefer, it can create a tunnel 180 feet long and 10 feet by 10 feet. Without randomness, it could do 600,000 cubic feet/a 600-foot tunnel per hour. That's a big difference if the beholder is working under time pressure, but it's mostly irrelevant to a beholder excavating its lair in safety.

Getting back to the OP's question, which assumes combat with a group of giff and thus allows full legendary actions by RAW: For any given eye ray, there is just under a 49% chance that a beholder will get to use it over the course of a round. You described a scenario where the beholders are in groups of 1-5. Thus, the chances of getting a given eye ray each round range from 49% (for a single beholder) to 97% (for a group of 5). So, the beholders in larger groups will almost always get to disintegrate at least once within the first round, which they can use to collapse a ceiling on the giff. They can also reliably use telekinesis, allowing them to create obstacles and throw rocks.

In addition, they can use anti-magic to split the giff party. Remember that hitting the source of the darkness effect with anti-magic shuts it down completely. So let's say the Dark Giff is in the center of the group, with 3 giff on the right and 3 on the left. A beholder targets the left side of the group with anti-magic, negating darkness. Then the beholders all unload their direct-fire eye rays on the giff on the right side (who are no longer hidden and also not in the anti-magic cone), meanwhile using telekinesis and disintegrate as indirect weapons against the giff on the left and the Dark Giff. With clever maneuvering, the beholders may even be able to isolate the Dark Giff, which will then find itself standing alone against multiple beholders.

Darkness is a potent spell against beholders, but far from a cure-all even if the beholders are played by RAW.

Edit: Reviewing the tactics you had in there originally--the Dark Giff is apparently going in alone to try and grapple a beholder and haul it out. This is suicidal. The grappled beholder merely has to turn its anti-magic eye on the Dark Giff, shutting down darkness, and then ready its action to go nuclear on all the other giff who are not in the anti-magic cone. More importantly, it can also go nuclear on the merc wizard! The weak point of any Concentration-based buff is the caster maintaining it.

 

[Celtavian]

Why the automatic assumption a ceiling will collapse when using disintegrate? It depends on what the surrounding support is like. The actual material the beholder hits turns to dust. For the collapse to work it must hit an area that would cause a collapse such as a support structure. Otherwise a collapse will not occur.

Blasting surrounding Giff would definitely work once he turns off the darkness with the antimagic eye.

Thanks for the update on the math, Dausuul. Three rolls, no duplicates is a 30% chance which would 180 10 foot cubs or 180,000 cubic feet. I was too focused on the cubes rather than the translation to cubic feet.

 

[Dausuul]

Why the automatic assumption a ceiling will collapse when using disintegrate? It depends on what the surrounding support is like. The actual material the beholder hits turns to dust. For the collapse to work it must hit an area that would cause a collapse such as a support structure. Otherwise a collapse will not occur.

True, but it's a beholder lair that they made themselves. I assume it would be designed with spots that could be collapsed via disintegration or telekinesis; the tactical value of being able to drop a ceiling on your opponents is considerable, and they can just disintegrate the rubble afterward.

 

[Scrivener of Doom]

I would just count on the giff to get lost as they're blind and chasing flying creatures.

 

[Saeviomagy]

Yes. I don't see how you could read the MM any other way.

The section on targeting is in the same paragraph as that about selecting eye rays, and talks about selecting 1 to 3 targets. Neither reading matches any kind of common sense, so it ends up being ambiguous.

 

[KarinsDad]

A universe filled with monsters and NPCs all using "optimal" strategies is boring and unrealistic. Try making your players declare actions in only six seconds and see how optimal their tactics are. The fact that players get to think in bullet time is a major advantage for the PCs.

The exact opposite can often be true IME.

The fact that I have so much time to figure out what to do means that I often forget what I was planning on doing.

Interestingly enough, my turn itself often takes less than 6 seconds. I roll my dice together with a single roll. I move my miniature quickly and succinctly. I do not count out hexes (or squares when I am in a square grid game), I just move the miniature. I'm very fast, but I sometimes forget something that I was planning on doing because I planned on doing it 6 minutes earlier in real time.