Anti-Stronghold Magic

Many strongholds employ magic to augment their defenses, so it’s only natural that attackers will use spells as well. Here are some spells particularly effective against strongholds, along with their cost if you hire an NPC spellcaster to cast them for you. Note that the prices below represent the minimum costs to have the spells cast for you by an NPC. Assuming you aren’t already paying the NPC as part of your attacking force, these prices should increase (by 100% or more) when cast in hazardous situations (such as part of a siege or other assault).

In addition to the strictly offensive spells discussed below, spells such as invisibility, fly, and teleport offer means that stronghold defenders must account for within the fantasy environment. Spells such as these can make even the highest walls and well-intentioned guards wholly ineffective. To counter such threats, the stronghold builder should be sure to be able to include options such as a chamber of seeing (see Wondrous Architecture in Chapter 2) or sentinels with access to see invisibility. To deal with flying character or creatures, an array of ranged weapons or puissant arcane spellcasters are required. It almost goes without saying, but constructing a stronghold with an open and undefended central courtyard is unwise when a dragon or wyvern could drop in. While teleport may be difficult to prevent without raising the stronghold’s cost (see the ethereal solid augmentation in Chapter 2), alarms can at least warn the castle’s inhabitants when the castle’s walls have been circumvented.

Disintegrate (660 gp)

This spell is the bane of many strongholds’ existence, because it cuts through everything—wood, stone, adamantine, and wall of force—with equal ease. A 10-foot cube of matter simply goes away. Attacking spellcasters typically aim this ray at the ground level of a stronghold to maximize the collateral damage they’ll do.

It’s worth noting that magic wall layers and magic augmentations get Fortitude saving throws against disintegrate, and if they succeed, they take 5d6 points of damage instead. Disintegrate can otherwise punch through multiple layers of the wall, because such a wall counts as a single multilayered object, not multiple objects.

Earthquake (910 gp)

The spell description notes that “most structures standing on open ground collapse,” but particularly well-built structures have a chance of standing even the strongest earthquake. Every wall section within the area of earthquake takes 3d6 ×10 points of damage. Start with the ground-floor wall sections and work upward, because collateral damage might make a difference. If it’s too time-consuming to adjacent and higher stronghold spaces just as you would if they were individual wall sections. In other words, each stronghold space becomes an average of its wall sections, and all the walls in a stronghold space share the same fate.

Earthquake further notes that underground strongholds “collapse the roof.” Because they’re surrounded on all sides by shifting, shaking earth, underground strongholds take more damage from the earthquake spell: 3d6 ×50 points of damage.

Finally, the cracks in the earth created by the spell will quickly drain moats and rivers, turning them into muddy ground that traps characters who fail Reflex saves (DC 15). Drained moats stay drained after earthquake ends, but rivers will flow again with a torrent of water, possibly drowning those stuck in the mud.

Soften Earth and Stone (60 gp)

This spell can deal “a moderate amount of structural damage” by softening the ground underneath an aboveground structure. If the stronghold sits on ordinary ground, such an attack deals 2d4 ×10 points of damage to each 10-foot section of wall so attacked. Strongholds that sit on stone surfaces find their surroundings turned to soft clay, dealing 1d4 ×10 points of damage to ground-level wall sections as they settle.

This spell isn’t typically effective against an underground stronghold such as a dungeon because it only affects unworked earth and stone, and dungeons have little of that. Natural caverns will be reduced to a clay-like consistency, enabling attackers to cut and reshape the walls.

Stone Shape (150 gp)

If all you need is a hole in a stone wall, this is your spell. It affects a minimum of 15 cubic feet, which can create a slightly larger than 2-foot-by-2-foot hole in a 3- foot thick wall—enough for a person to climb through. Multiple castings can entirely compromise the protection afforded by stone barriers.

You can also use stone shape to weaken an existing structure by thinning a large area of wall. For instance, you can shave a foot of thickness from a 3-foot-thick stone wall in a 15-square-foot area, reducing its hit points by a third.

Transmute Rock to Mud (450 gp)

Much like soften earth and stone, transmute rock to mud only affects unworked stone, so it can’t be used against most strongholds directly. If it can reach natural rock underneath a stronghold’s foundation, it deals 2d4 ×10 points of damage to each wall section on the ground level, just as soften earth and stone does. Note that unlike its lower-level counterpart, transmute rock to mud affects two 10-foot cubes per level, and the spell’s area is shapeable.

Warp Wood and Wood Shape (60 gp)

Each of these spells has a similar effect upon wooden barriers, such as doors or shuttered windows: it renders them useless. A locked door doesn’t provide much protection if it’s bent or deformed. Note that wood shape has a larger effect, though it requires the caster to touch the target.