D&D 5E Phase Spiders and Surprise

[Plaguescarred]

But the spiders don't have enter the material plane until after initiative has been rolled, so the PCs see no threaths at the start of combat and are thus surprised.

While a DM can always rule otherwise, the surprise rules as written are not automatic, instead offering a chance to not be surprised by noticing enemies using Stealth vs Perception contest. Which what you say doesn't offer any chance.

Scenario 1: If initiative is rolled before the phase spider emerge, the PC may loose or win it but not act before the spiders anyway, not knowing about their presence. When the spiders emerge on their turn the PCs would notice them not being hidden and be able to take reactions if they lost initiative where they wouldn't if they were surprised.

Scenario 2: If initiative is rolled after the phase spider emerge, the PC may loose or win it and act before the spiders, knowing about their presence. When the spiders emerge at the start of combat the PCs would notice them not being hidden and be able to take reactions if they lost initiative where they wouldn't if they were surprised. In this scenario the spiders were allowed to take an action to emerge before initiative which is not RAI as per Sage Advice http://dnd.wizards.com/articles/features/rules-answers-november-2015

"If anyone is surprised, no actions are taken yet. First, initiative is rolled as normal. Then, the first round of combat starts, and the unsurprised combatants act in initiative order."

So bottom line is PC might still possibly be left unable to act before the spider emerge, but in either case it would leave them with the possibility to react.

 

[Sorcerers Apprentice]

While a DM can always rule otherwise, the surprise rules as written are not automatic, instead offering a chance to not be surprised by noticing enemies using Stealth vs Perception contest. Which what you say doesn't offer any chance.

Scenario 1: If initiative is rolled before the phase spider emerge, the PC may loose or win it but not act before the spiders anyway, not knowing about their presence. When the spiders emerge on their turn the PCs would notice them not being hidden and be able to take reactions if they lost initiative where they wouldn't if they were surprised.

Scenario 2: If initiative is rolled after the phase spider emerge, the PC may loose or win it and act before the spiders, knowing about their presence. When the spiders emerge at the start of combat the PCs would notice them not being hidden and be able to take reactions if they lost initiative where they wouldn't if they were surprised. In this scenario the spiders were allowed to take an action to emerge before initiative which is not RAI as per Sage Advice http://dnd.wizards.com/articles/features/rules-answers-november-2015

"If anyone is surprised, no actions are taken yet. First, initiative is rolled as normal. Then, the first round of combat starts, and the unsurprised combatants act in initiative order."

So bottom line is PC might still possibly be left unable to act before the spider emerge, but in either case it would leave them with the possibility to react.

But the phase spiders are trying to be stealthy, and there is an implied stealth vs perception contest. But the PCs automatically fail the test since their senses do not extend into the ethereal plane, like how a blinded character will autofail any check that requires sight.

Thus when combat starts the PCs are surprised since they haven't noticed any threat.

 

[Plaguescarred]

But the phase spiders are trying to be stealthy, and there is an implied stealth vs perception contest. But the PCs automatically fail the test since their senses do not extend into the ethereal plane, like how a blinded character will autofail any check that requires sight.

Thus when combat starts the PCs are surprised since they haven't noticed any threat.

You cannot make a contest with creatures not even present! If the spiders are trying to be stealthy, they've taken the Hide action and made a Stealth check, and will be noticed the moment they emerge in plain view, unless they emerge in some form of obscurement, at which point there'd be a chance to not be noticed when the Stealth vs Perception contest would be made.

Otherwise as per your analogy people would take the Hide action, make a Stealth check and determine that you can't notice them since you were not there when they did, thus never being noticed! Perception check is made when things can possibly be perceived.

 

[Sorcerers Apprentice]

You cannot make a contest with creatures not even present! If the spiders are trying to be stealthy, they've taken the Hide action and made a Stealth check, and will be noticed the moment they emerge in plain view, unless they emerge in some form of obscurement, at which point there'd be a chance to not be noticed when the Stealth vs Perception contest would be made.

Otherwise as per your analogy people would take the Hide action, make a Stealth check and determine that you can't notice them since you were not there when they did, thus never being noticed! Perception check is made when things can possibly be perceived.

The spiders are present, but in the ethereal plane, so they can't be directly interacted with. but they are still present. It is true they will be noticed as soon as they phase into the material plane, so they will not get the "unseen attacker" advantage. But this happens after surprise has been determined for the combat, so the PCs will be surprised unless they have special abilities to either percieve the ethereal or negate the surprised condition.

 

[Plaguescarred]

The spiders are present, but in the ethereal plane, so they can't be directly interacted with. but they are still present.

No they are not present they are on a different plane of existence!

It is true they will be noticed as soon as they phase into the material plane, so they will not get the "unseen attacker" advantage. But this happens after surprise has been determined for the combat unless they have special abilities to either percieve the ethereal or negate the surprised condition.

No otherwise what you say would result in people that hide before creatures show up to always automatically surprise them unless they could see through walls or distance when they did take the Hide action!

 

[Sorcerers Apprentice]

No they are not present they are on a different plane of existence!

They are on a different plane that overlaps the material plane. Is it unclear to you what the ethereal plane is? The spiders are not physically present but ethereally present. Significantly, they can percieve the material plane and so can see the PCs. (Unless the PCs are trying to be stealthy and succeed on a stealth contest vs the spider's perception checks.)

No otherwise what you say would result in people that hide before creatures show up to always automatically surprise them unless they could see through walls or distance when they did take the Hide action!

I have no idea how you manage to infer that from my posts.

 

[Plaguescarred]

They are on a different plane that overlaps the material plane. Is it unclear to you what the ethereal plane is? The spiders are not physically present but ethereally present. Significantly, they can percieve the material plane and so can see the PCs. (Unless the PCs are trying to be stealthy and succeed on a stealth contest vs the spider's perception checks.)

The ethereal plane, deep or border, is still a different plane of existence that doesn't allow interaction with the prime material plane even if sight is possible to it.

Not because i can see you through walls or in the distance via clairvoyance or ethereal border when i take the Hide action and you can't notice me yet, that when we meet i will automatically surprise you because you couldn't notice me and i could when i took the Hide action is what i was saying.

I disagree with you creatures being on seperate plane of existence considered present. Like i said DM can always rule it this way if he want but automatic surprise with no chance of noticing enemies are just gotchas.

 

[Plaguescarred]

The spiders are present, but in the ethereal plane, so they can't be directly interacted with.

Here you let prime material creature's Perception interact with ethereal creature's Stealth in a contest and declare failure.

 

[Sorcerers Apprentice]

The ethereal plane, deep or border, is still a different plane of existence that doesn't allow interaction with the prime material plane even if sight is possible to it.

Not because i can see you through walls or in the distance via clairvoyance or ethereal border when i take the Hide action and you can't notice me yet, that when we meet i will automatically surprise you because you couldn't notice me and i could when i took the Hide action is what i was saying.

I disagree with you creatures being on seperate plane of existence considered present. Like i said DM can always rule it this way if he want but automatic surprise with no chance of noticing enemies are just gotchas.

You can certainly rule that the spiders can't start combat until they phase to the material plane, but there's nothing in the rules text that says so. The situation is not really that different from a case where the spiders are invisible and have made excellent stealth rolls.

Imagine that the situation is reversed, the players have managed to become ethereal and want to abush a group of unsuspecting enemies on the material plane. You would not permit this?

 

[Sorcerers Apprentice]

Here you let prime material creature's Perception interact with ethereal creature's Stealth in a contest and declare failure.

Yes, because perception is not a direct interaction.