D&Dtools1

By infusing the nearby landscape with power stolen from the Plane of Shadow, you make the surrounding terrain a more savage, dangerous place.
The spell's exact effects vary with the terrain upon which it is cast.
Desert: Shadow landscape transforms a desert into a place where no one goes willingly.
The average temperature increases by 30 degrees, or decreases by 30 degrees if the desert is actually a tundra (see Cold Dangers and Heat Dangers, pages 302-303 of the Dungeon Master's Guide).
Sandstorms (or snowstorms if in a tundra) blow through a shadow landscape desert on an hourly basis.
Forest: Forests augmented with a shadow landscape spell become frightening places where a canopy of rotting leaves blocks the sun and all the trees are strangely twisted.
Spaces with light undergrowth have heavy undergrowth
instead, and spaces covered with heavy undergrowth grasp at passersby as if an entangle spell had been cast on them (Reflex partial at the shadow landscape's DC).
Hill: Even gentle hills become more treacherous under the effects of a shadow landscape spell.
Light undergrowth becomes heavy undergrowth in hill terrain under the effects of shadow landscape, and slopes seem steeper than their elevation would indicate.
It takes two squares to move uphill on a gradual slope, and four squares to move uphill on a steep slope.
Cliffs have frequent overhangs and are made of crumbling rock, requiring a DC 25 Climb check to ascend or descend.
Marsh:Marshes seem swampier and more forbidding.
Half the undergrowth spaces in the marsh become quicksand (described on page 88 of the Dungeon Master's Guide).
Mountain: The mountains become places of jagged peaks, slippery slopes, and howling winds.
Cliffs and chasms require a DC 25 Climb check to scale.
Creatures who fail Climb checks or make loud noises have a 10% chance of starting an avalanche (described on page 90 of the Dungeon Master's Guide).
Altitude effects are one category worse: areas lower than 5,000 feet are treated as the 5,000- to 15,000-foot category,
and anything above 5,000 feet is treated as being above 15,000 feet.
Plain:Only natural grasslands change as a result of shadow landscape, but they become wide-open spaces with stands of thick bushes where thunderstorms and tornados are frequent.
Half the spaces with undergrowth (light or heavy) grasp at passersby as if an entangle spell had been cast on them (Reflex partial at the shadow landscape's DC).
Underground:Ordinary dungeons aren't affected by shadow landscape, but naturally occurring caverns are.
Natural stone floors take 4 squares of movement per space to enter.
Stalagmites cover 10% of the available floor space.
In addition to the terrain-specific effects, the shadow landscape spell worsens the weather within the spell's area.
When rolling random weather on Table 3-23 in the Dungeon Master's Guide (or a similar table specific to the local area), roll twice and take the higher result.
In plains terrain, roll three times and take the highest result.
Don't roll random weather underground.
You don't suffer the terrain-specific effects (entangling terrain, hindrances to movement, altitude effects, higher Climb DCs, and so on) of a shadow landscape you've created.
When you cast shadow landscape, you can designate one creature per four caster levels as a designated traveler.
Creatures so designated don't suffer the terrain-specific effects of the shadow landscape spell, but they're still subject to the bad weather.
You can also designate one or more animals, plants, or magical beasts native to the spell's area as shadow guardians of the landscape.
You can designate 1 HD of creature per caster level, split up however you like.
For example, a 20th-level druid could designate two treants (7 HD each) and a dire wolf (6 HD) as shadow guardians.
As long as the designated guardians remain within the spell's area, they have a friendly attitude toward you and the travelers you've designated, and also gain the following special qualities: resistance to cold 10, darkvision 60 ft.; damage reduction 5/magic, evasion, and low-light vision.
If the creature already has one or more of these special qualities, use the better value.