Concealment, reach weapons, blind sense and AOOs

[Grand Poobah]

Giants,

I've created an NPC, lets call him Bob. Bob's a Duskblade 5, Dragon Disc 6; trip related feats, including combat reflexes and blind fighting.

He wields a guisarme, so he's got reach. He can cast obscuring mist too (adjacent enemies have concealment, enemies >5' have total concealment). Being DD 5 he gets 30 'blindsense too.

I'm curious as to know if I'm ruling this correctly:

On Bob's first round, he drinks a potion Enlarge Person, moves to within melee range of, but not adjacent to, as many enemies as possible, use Quick Cast OM.

Enemies can't visually see Bob. They can't take 5' steps due to restricted visibility neither. One of them moves, which Bob's blindsense picks up triggering an AOO. Bob gets +2 on this roll, and the enemy loses their DEX AC bonus because the enemy player can't see him. Bob goes for a Trip attempt, which hits, passes the concealment mischance and puts the enemy prone. Bob gets the Trip's feat free melee attack with the +2 invisibility bonus, no DEX to AC, and +4 to hit because they're now also prone. Bob rolls nat 20 and confirms the critical doing lots of damage.

The enemy survives and takes a 2nd move action to, stupidly, stand up. Bob's blindsense picks up this movement, triggering a 2nd AOO, and everything plays out identically as it did in the 1st AOO, but this time Bob's enemy dies. Pity Bob's not got Cleave otherwise he could got another attack, which he'd use to trip another enemy etc.

I'm particularly interested in whether blindsense would pick up someone standing up thereby allowing the AOO to trigger. Also, are the bonuses and penalties applied correctly. Finally, you can trip on a cleave attack can't you?

Thanks

[Khedrac]

Simply put, I am sorry but no.

You are counfusing blindsense and blindsight, If Bob had blindsight then the above would be true, but he doesn't.
With blindsense he knows which square opponents are in. Without some other way of knowing where they are he's not going attack the wrong square, but they still have total concealment from him (no AoOs) so there's a 50% miss chance whenever he attacks them.


BLINDSIGHT AND BLINDSENSE
Some creatures have blindsight, the extraordinary ability to use a nonvisual sense (or a combination of such senses) to operate effectively without vision. Such sense may include sensitivity to vibrations, acute scent, keen hearing, or echolocation. This ability makes invisibility and concealment (even magical darkness) irrelevant to the creature (though it still can’t see ethereal creatures). This ability operates out to a range specified in the creature description.

Blindsight never allows a creature to distinguish color or visual contrast. A creature cannot read with blindsight.
Blindsight does not subject a creature to gaze attacks (even though darkvision does).
Blinding attacks do not penalize creatures using blindsight.
Deafening attacks thwart blindsight if it relies on hearing.
Blindsight works underwater but not in a vacuum.
Blindsight negates displacement and blur effects.

Blindsense: Other creatures have blindsense, a lesser ability that lets the creature notice things it cannot see, but without the precision of blindsight. The creature with blindsense usually does not need to make Spot or Listen checks to notice and locate creatures within range of its blindsense ability, provided that it has line of effect to that creature. Any opponent the creature cannot see has total concealment (50% miss chance) against the creature with blindsense, and the blindsensing creature still has the normal miss chance when attacking foes that have concealment. Visibility still affects the movement of a creature with blindsense. A creature with blindsense is still denied its Dexterity bonus to Armor Class against attacks from creatures it cannot see.

[Telonius]

Here's the SRD on Blindsense (http://www.d20srd.org/srd/specialAbilities.htm#blindsightAndBlindsense):


Blindsense
Other creatures have blindsense, a lesser ability that lets the creature notice things it cannot see, but without the precision of blindsight. The creature with blindsense usually does not need to make Spot or Listen checks to notice and locate creatures within range of its blindsense ability, provided that it has line of effect to that creature. Any opponent the creature cannot see has total concealment (50% miss chance) against the creature with blindsense, and the blindsensing creature still has the normal miss chance when attacking foes that have concealment. Visibility still affects the movement of a creature with blindsense. A creature with blindsense is still denied its Dexterity bonus to Armor Class against attacks from creatures it cannot see.

I think it is a bit of a gray area. It depends on how you interpret "notice" and "locate." If it just means, "notice that a creature is there" or "locate the square it's in," then I don't think it would pick up motion within the square. If it means something more like, "Notice when it moves," or "locate where in the square it is," Blindsense would allow for the AoO.

Personally I think that the fact that you still have to roll the Concealment percentile suggests that you can only locate the square it's in, and can't sense what it's doing specifically or whether it's standing, sitting, or prone.

EDIT: As for tripping on a cleave attack, yes, you can use your Cleave attack to trip someone, but you have to use the same weapon you used to drop the other guy. The table way down at the bottom of this (http://www.d20srd.org/srd/combat/actionsInCombat.htm#) page, Footnote 2:


These attack forms substitute for a melee attack, not an action. As melee attacks, they can be used once in an attack or charge action, one or more times in a full attack action, or even as an attack of opportunity.

Cleave isn't specifically mentioned here, but the general rule is that they can substitute for a melee attack. Cleave grants an extra melee attack, so you can use it.

[Khedrac]

The rules on blindsense specify that targets still have total concealment without another way to see them.


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.

No AoOs is RAW

[Elkad]

No AoOs is correct. But it's solvable with those See Through Fog lenses.

Someone chime in with the name and book number?

Or by getting actual Blindsight somehow.

[Grand Poobah]

Completely missed that you can't take AOOs against concealed enemies.

Found Blindfold of True Darkness in the MiC (30' Blindsight) so I've swapped his gear around.

Thanks

[Elkad]

I guess I was thinking of Fogcutter Lenses above, which are PF.

3.5 Cloak in here (http://archive.wizards.com/default.asp?x=dnd/fw/20050311a)that lets you see and move in fog (including Solid Fog), 31k. More expensive, but if you can manage a Solid Fog, or are worried about the party staying at range, it's a consideration.

[Crake]

They can't take 5' steps due to restricted visibility neither.

I don't believe obscuring mist restricts visibility enough to the point where you can't take a 5ft step. You need to be practically blind for that to be the case.