Rules for Navigating In A Fog?

[Dralnu]

The situations:
Orcs and zombies are attacking the PCs. In the middle of the fight, a PC uses Obscuring Mist (http://www.d20srd.org/srd/spells/obscuringMist.htm). All the PCs happen to be 10ft. away from the NPCs.

What's something reasonable these orcs and zombies do? Zombies are mindless and being controlled by two orc clerics (cleric4 of Nerull). The orcs are smart, but they have no means of dispelling / countering the mist. If I want them to try and find the PCs they were just fighting, do I roll for random directions to wander in or what?

Never had to deal with fogs before. Help!

[Flickerdart]

The caster is at the centre of the spell - so the Clerics can freely firebomb that square. They can also just station a zombie in each square of the effect until one bumps into an adventurer, or simply wait until the spell fades and use the time to patch themselves up.

[holywhippet]

The clerics should order the zombies to keep bull rushing through the effected area hoping to hit a PC.

[Drachasor]

By default? I'd say the Orcs are smart enough to get out of the mist and surround it, assuming that's feasible. If surrounding isn't a good idea, then they'd go to the most likely exit point for the PCs.

Zombies? Run to intercept the PCs in the fog. If a PC was stationary, they'd run to the last seen spot. If a PC was moving, they'd run to meet up with the PC assuming he was moving in the same direction. If the zombies HEAR the PCs, (listen check), then they follow that sound. Orcs should probably also make listen checks to help make a better decision.

[Dralnu]

What I'm really wondering is if there's any rules about navigating in a fog like that. Do they need to make listen checks? Will they lose track of where they are and move in the wrong direction? Do they have to move at half speed or something? I can't find this information anywhere in the DMG or PHB, which is puzzling since you'd think they'd have information about how their own spells actually work...

EDIT: Clarified the title.

[LansXero]

What I'm really wondering is if there's any rules about navigating in a fog like that. Do they need to make listen checks? Will they lose track of where they are and move in the wrong direction? Do they have to move at half speed or something? I can't find this information anywhere in the DMG or PHB, which is puzzling since you'd think they'd have information about how their own spells actually work...

EDIT: Clarified the title.

If you know anyone who plays warhammer ask them for a scatter dice and use it to adjudicate stuff like that. If you dont... draw 4 arrows diagonally, all different to each other, and tape them to the sides of a d6, then use it to adjudicate stuff like that. Its nowhere near RAW but it, imho, very well represents random direction stuff like getting lost in a fog or which side the giants topples.

[Drachasor]

What I'm really wondering is if there's any rules about navigating in a fog like that. Do they need to make listen checks? Will they lose track of where they are and move in the wrong direction? Do they have to move at half speed or something? I can't find this information anywhere in the DMG or PHB, which is puzzling since you'd think they'd have information about how their own spells actually work...

EDIT: Clarified the title.

No, you don't need to make checks. Do not assume even the zombies are so incompetent that they can't manage to move 20 feet or twice that in a relatively straight line. There's also more than enough visibility.

If a spell doesn't say it imposes penalties, then don't make up more penalties for it to impose. Most of the time you'll honestly end up making enemies act like utter morons by mistake.

[Seffbasilisk]

RAW already has a function for random direction on a grid. D8, starting with 'North' as 1.

I'd have the orcs step out and AoE, while the zombies mill trying to grab.

[tyckspoon]

What I'm really wondering is if there's any rules about navigating in a fog like that. Do they need to make listen checks? Will they lose track of where they are and move in the wrong direction? Do they have to move at half speed or something? I can't find this information anywhere in the DMG or PHB, which is puzzling since you'd think they'd have information about how their own spells actually work...

EDIT: Clarified the title.

Not sure where it is in the physical books (DMG, I think), but this is the section (http://www.d20srd.org/indexes/carryingMovementExploration.htm) in the SRD. It's under Tactical Movement- Hampered Movement. Basically, hampered vision has the same effect as difficult terrain- half movement and you can't run or charge through areas where you can't see properly.

For locating things within the fog, it depends on how dense the fog is.. 'normal' environmental fog only gets to 20% concealment, so you can still see your enemies, but Obscuring Mist blocks all vision past 5 feet, so you'll need alternate means of locating your targets. Listen checks would be the most accessible, assuming you aren't running weird zombies with tremor/blindsense; it's generally not too hard to figure out the location of a combat-ready opponent 10 feet away from you, especially if he ends up in contact with somebody and takes a swing at him (I think it's like a base DC -5 to hear him, maybe DC 5 to pinpoint?)

[ericgrau]

Invisibility and darkness have similar rules. I imagine fog falls into the same category: http://www.d20srd.org/srd/specialAbilities.htm#invisibility

Basically a DC 20 listen check will find you the square wherein most standard and full round actions happen. A DC 0 check gives general direction. For most move actions the DC is the move silently check result for general direction, and that plus 20 for the square. You also move at half speed. None of these checks stop the 50% miss chance from concealment. Even on a failed check the player may guess at a square to try.

I do not advocate making people flail around and move randomly like idiots in darkness or fog or when blind. You're saying "Hey I'm a legendary hero, but if I can't use my eyes I might as well be paraplegic". Also makes a lot of low level spells much more powerful than they ought to be.

[Dralnu]

With hampered movement and invisbility, you guys have helped me figure out how to navigate this:
The area inside the fog is hampered movement (http://www.d20srd.org/srd/movement.htm#hamperedMovement) so each square counts as two and you can't charge. Anyone more than 5ft. away (fully concealed) will use the invisibility rules. (http://www.d20srd.org/srd/specialAbilities.htm#invisibility) So, DC 0 +1 per 10ft. gets the general direction of an invisible creature (person in fog you can't see) in combat, and if you beat the DC by 20 then you can pinpoint the creature's location. If you're in an adjacent square, the target is no longer "invisible" and you automatically pinpoint the target, but still has the benefit of concealment (20% miss).

Pretty simple for a level 1 spell. Now I just need to make all those rolls for my 11 mooks. :smallsigh:

Thank you everyone for your help!

[ericgrau]

Ya that's about it, but only if the creature did something noisy without moving silently afterwards (at 1/2x1/2=1/4 speed by the way). Casting, attacking, and most other standards/full-rounds are always noisy. But for sanity's sake on 11 mooks you might want to have all 11 mooks attempt to move and then attack so you don't have to track which ones made noise.