Invisibility vs. scent

[Patrick O'Duffy]

We've recently added a ninja to my Eberron game, and in the first session the PCs fought a group of trained blink dogs. The question came up as to whether the ninja could effectively use its sudden strike ability (which relies on opponents being denied their Dex bonus) against the dogs.

The dogs have scent, which according to the SRD "A creature with the scent ability can detect an invisible creature as it would a visible one.' Does this mean that the dogs (or any other critters with scent) do not lose their Dex bonus against an invisible attacker, such as a ninja using ghost step?

Also, is this an automatic process? The SRD also states "Noting the direction of the scent is a move action. If it moves within 5 feet of the scent’s source, the creature can pinpoint that source." Does that imply that the dogs would need to use a move action to detect the ninja and negate its invisibility?

These are pretty obvious questions, yet in 5+ years of running D&D it's the first time they've come up for me. Weird.

 

[SteelDraco]

A creature with scent can determine what square an opponent is in, but not target them well enough to negate concealment. They keep the 50% miss chance, but don't have to worry about figuring out which square to attack, and they automatically know when there's an invisible opponent around.

Some creatures have Blindsight that's described as Scent keen enough to negate concealment, but that's not normal.

 

[Darklone]

These dogs needs Blindfight.

Yupp, the ninja can sudden strike them.

 

[Patrick O'Duffy]

A creature with scent can determine what square an opponent is in, but not target them well enough to negate concealment. They keep the 50% miss chance, but don't have to worry about figuring out which square to attack, and they automatically know when there's an invisible opponent around.

That's pretty clear from the rules, yeah, but doesn't address whether the creature loses its Dex bonus against an invisible attacker.

Or to put it another way - the rules are clear about scent attacking invisibility, but less clear about invisibility attacking scent.

 

[Doctor DM]

Yeah, I'm wondering about this too. My party has a fight with a genie coming up, and the druid has a wolf for his companion.

Do you have to actively smell, or does the wolf just automatically detect the creature?

 

[Arkhandus]

Here are some quotes from the SRD regarding Scent, that may be relevant to your question.

A creature with the scent ability can detect opponents by sense of smell, generally within 30 feet. If the opponent is upwind, the range is 60 feet. If it is downwind, the range is 15 feet. Strong scents, such as smoke or rotting garbage, can be detected at twice the ranges noted above. Overpowering scents, such as skunk musk or troglodyte stench, can be detected at three times these ranges.

The creature detects another creature’s presence but not its specific location. Noting the direction of the scent is a move action. If it moves within 5 feet of the scent’s source, the creature can pinpoint that source.

A creature with Scent will notice that an invisible creature is nearby (if they're within the Scent ability's range), but they won't know where that invisible creature is.

The Scent-possessing creature would still be denied a Dexterity bonus to AC against the invisible foe, and the invisible attacker would still get +2 on their attack rolls against the creature with Scent.

Once the invisible foe is within 5 feet, the creature with Scent will know which space the invisible foe occupies, but will still have to deal with the invisible one's concealment (50% miss chance) and will still be unable to see any attacks by the invisible foe, so will continue to be denied a Dex bonus to AC, and the invisible guy will still get +2 on attack rolls against them.

 

[Patrick O'Duffy]

Here are some quotes from the SRD regarding Scent, that may be relevant to your question.

Perfect. Many thanks!