Tremorsense vs Ghost Step

[swordsmasher]

Boy, did i get into last night!

Facing an elder Xorn, the Ninja PC decided to Ghost Step, and incurred an attack of opportunity. The Xorn hit with a claw, and dealt damage. Over the next hour it was DM vs Players, as they said a Ghost Stepping Ninja can't be seen, even with Tremorsense.

I say it is, at least until the Ninja is 10th level and can go ethereal.

So, to make the peace, i took back the attack and gave the pc his hp's back.

But I am positive I am correct! Anyone help?

 

[DevoutlyApathetic]

Tremorsense

A creature with tremorsense automatically senses the location of anything that is in contact with the ground and within range. Aquatic creatures with tremorsense can also sense the location of creatures moving through water.

If no straight path exists through the ground from the creature to those that it’s sensing, then the range defines the maximum distance of the shortest indirect path. It must itself be in contact with the ground, and the creatures must be moving.

As long as the other creatures are taking physical actions, including casting spells with somatic components, they’re considered moving; they don’t have to move from place to place for a creature with tremorsense to detect them.

The PC was invisible and had total concealment. Total concealment negates AoO. The Xorn knew where the PC was but couldn't "see" him. Xorn doesn't get an AoO.

All Tremorsense says is that they know where they are which doesn't do anything to eliminate concealment.

Afraid I can't help you as they were right.

Also an hour of discussion on a rule? This is exactly the kind of thing that shouldn't happen during a game. As a DM you need the trust level to allow you to say "This is what it is now, we can talk more later but for now we move the game forward." If you don't have that level of trust it's something I'd work on.

The implied obligation of such trust is that you deserve it by having learned the rules.

 

[rowport]

Devout-

I agree with you on the in-game rules debate being a waste of time and energy. That has been a problem with our group that I think we *finally* got past by agreeing to deal with stuff like that out-of-game later.

That said, I am not sure I agree with your interpretation! If "A creature with tremorsense automatically senses the location of anything that is in contact with the ground and within range" then why would the Xorn have to see the character to attack him? My ninja/cleric has had the same problem Ghost Stepping (heh) past an opponent who had Scent, and therefore knew his location to take an AoO. Are you saying that even if location is known from extra-sensory perception, that you cannot take AoOs because you cannot literally "see" the opponent? That does not seem right to me.

Tremorsense?
Blind-sight?
Scent?
Other funky senses?

Edit: To be clear, when my Ninja was surprised by Scent, I did not argue the rules, but did go, "Oh, Crap!"

 

[Patryn of Elvenshae]

That said, I am not sure I agree with your interpretation! If "A creature with tremorsense automatically senses the location of anything that is in contact with the ground and within range" then why would the Xorn have to see the character to attack him?

Because ...

Total Concealment: If you have line of effect to a target but not line of sight he is considered to have total concealment from you. You can’t attack an opponent that has total concealment, though you can attack into a square that you think he occupies. A successful attack into a square occupied by an enemy with total concealment has a 50% miss chance (instead of the normal 20% miss chance for an opponent with concealment).

You can’t execute an attack of opportunity against an opponent with total concealment, even if you know what square or squares the opponent occupies.

 

[Lord Pendragon]

Are you saying that even if location is known from extra-sensory perception, that you cannot take AoOs because you cannot literally "see" the opponent?

Yes, this is how it works. Note that you don't even need an exotic ability to sense the location of an invisible, or Ghost Stepping foe. A Listen check can do it.

Tremorsense?
Blind-sight?
Scent?
Other funky senses?

It depends on the sense. Blindsight actually allows you to "see" your opponent, albeit with something other than eyes. Sonar, for instance, provides not only location, but shape for the attacker to utilize. Tremorsense, Scent, and the Listen check, on the other hand, merely provide the square in which the invisible foe is positioned. You get to make an attack at the correct square, but still suffer the effects of total concealment.

At least, this is my understanding.

 

[rowport]

Thanks for the replies, guys! That is interesting... I will pass along the thread link to my DM. In fairness, he *might* have rolled against the concealment and I just forgot or did not notice it, but I am really sure that Scent was used for an Attack of Opportunity, which is specifically prohibited in Paytrn's SRD quote above. So, it looks like:

1. Attacks of Opportunity require seeing the opponent (not just knowing his square). Blindsight works to "see" him.
2. Regular Attacks can be made with an invisible opponent knowing the right square, but with a 50% miss chance. Knowing the right square might come from Scent, Tremorsense, or a good Listen check.

Is that right?

 

[Patryn of Elvenshae]

That's correct, rowport.

EDIT:

Also, you can add "a lucky guess" to your list in #2.

 

[Artoomis]

I think you guys are right about tremorsense NOT negating concealment - this makes a world of difference when fighting, for example, a Remorhaz, as we recently did. I'll pass this on to my DM.

 

[Infiniti2000]

Just to be sure the tremorsense rule actually gets quoted:

Like in the very first response?

 

[Artoomis]

Like in the very first response?

Whoops - second post, actually. I guess I skimmed along to quickly.

Sorry. I'll edit it out for better thread readability.