How do you run Phase Spiders?

[delta]

How would you run a combat with a Phase Spider? Particularly: How would you determine when it's out-of-phase and not subject to normal player attack?

(Perhaps a short example combat would clarify?)

[Desparil]

I started with 2nd Edition, so I've always stuck with the approach specified there - modified a little if I'm running a different version that uses a d6 or a d20 for initiative rather than a d10.

The relevant passage from the Monstrous Manual: "if a phase spider wins initiative by more than 4, it attacks and phases out before its opponent has a chance to strike back"

[Deleted]

In BECMI, the Phase Spider is the "Planar Spider", and has a 75% chance of avoiding a counter-attack because it automatically gains initiative when attacking, except against a hasted opponent. I think this is a pretty adequate system because it gets the point across. The 2e method also works just fine. It's just two ways of representing the same attributes of the creature.

[dicebro]

Jan 2, 2022 0:18:40 GMT -6 delta said:

How would you run a combat with a Phase Spider? Particularly: How would you determine when it's out-of-phase and not subject to normal player attack?

(Perhaps a short example combat would clarify?)

Here are some off the cuff methods that are helpful for most anything, especially solo: A) roll a d6 and a 1 or 2 either succeeds or fails depending on how You call it just before the roll.  (B) roll 2 dice. The first sets the challenge number. The second die roll must be less than (or greater than) the first. 

[kipper]

I had the idea that they could only be attacked if the players won initiative that round. If the players lose initiative, then the phase spiders phase out before they can be attacked. (This method would require re-rolling initiative every round).

[delta]

FYI, Sage Advice in Dragon #131 (1988, one year before 2E came out), said the following. Even if someone followed that, seems to me like it needs more detail, like what happens if the phase spider doesn't win initiative. Can it choose to take no action and sit out-of-phase for the round?

A phase spider can phase in, attack, and phase out before its opponents can strike if it has the initiative; otherwise, it may be attacked normally. Phase spiders go to the Ethereal plane when they phase out, so ethereal beings can attack them.

[howandwhy99]

My understanding is Phase Spiders can only phase out of the PM for 1 round. So I have them phase back in at the start of every round. But they phase out as a choice, an ability during their actions.

I select and note a re-entry point at the moment they phase out so they don't have knowledge of the changed situation they are phasing back into.

I "cheat" though. I don't limit their re-entry target by line of sight, just distance.

[delta]

Jan 2, 2022 12:30:43 GMT -6 howandwhy99 said:

My understanding is Phase Spiders can only phase out of the PM for 1 round...

That's certainly different from my reading. Where the Sup-I text says, "... bringing itself back only when it is ready to deliver its poisonous bite...", it sounds like it's safely out-of-phase until it decides to attack again ("ready" indicating it gets an intentional choice about it).

[Mordorandor]

Jan 2, 2022 0:18:40 GMT -6 delta said:

How would you run a combat with a Phase Spider? Particularly: How would you determine when it's out-of-phase and not subject to normal player attack?

(Perhaps a short example combat would clarify?)

My reading has been, from an OD&D simultaneous movement perspective, they’re impervious to all attacks until the phase door spell (or something similar) is used. They’re very nasty things all together. If one wants to make them “more balanced,” they might fight as if they’re just another fantastic monster, enabling fantastic monsters and spells to affect them while they’re phased. If one is using 1d6 to determine initiative, then the 1d6 rolls establish whether foes can fight the phase spider any given turn.

[Desparil]

Jan 2, 2022 12:08:19 GMT -6 delta said:

FYI, Sage Advice in Dragon #131 (1988, one year before 2E came out), said the following. Even if someone followed that, seems to me like it needs more detail, like what happens if the phase spider doesn't win initiative. Can it choose to take no action and sit out-of-phase for the round?

A phase spider can phase in, attack, and phase out before its opponents can strike if it has the initiative; otherwise, it may be attacked normally. Phase spiders go to the Ethereal plane when they phase out, so ethereal beings can attack them.

At least in 2E, actions are declared before rolling initiative for the round. So by the time you know if it will be able to phase out quickly enough to avoid retaliation, it has already committed to attacking for the round. Compared to the BECMI version, they do get a -3 bonus to initiative to help them out, though the end result is still considerably less than the Planar Spider's 75% chance. Probably a good thing on balance, from the perspective of making it less frustrating for players to fight against them - not being able to attack them three-quarters of the time makes them obscenely deadly, with an average of four save-or-die venomous bites per spider for every round of retaliation the PCs get.