Ice Sheet
Spell — see Magic and Spellcasting for the rules and the Spell Index for the full list.
Arcane 3, Divine 5 Type: elemental (water), wall
Range: 45’ Duration: perpetual
This spell instantly freezes a large volume of water in range, creating a thick sheet of ice that floats on the remaining water. The ice sheet created by the spell can be either 1”, 4”, 1’, or 10’ thick.
A 1” thick ice sheet can have a maximum surface area of 180,000 square feet (approximately 240’ radius), a 4” thick sheet can have a maximum surface area of 45,000 square feet (approximately 120’ radius), a 1’ thick sheet can have a maximum surface area of 15,000 square feet (approximately 70’ radius), and a 10’ thick sheet can have a maximum surface area of 1,500 square feet (approximately 20’ radius).
The ice sheet’s surface area and thickness cannot exceed the surface area and depth of the body of water from which it is created. It cannot be evoked so that it appears where objects or creatures already are, but it can be evoked over creatures under the water. The water inside a living creature cannot be turned into an ice sheet, no matter how large the creature is.
As ice is less dense than water, the top of the ice sheet will be about 10% higher than the surface of the water. A 1” thick ice sheet will be about 1/8” above the water, a 4” thick sheet will be about 3/8” above the water, a 1’ thick one will be about 1.25” above the water, and a 10’ thick one about 1’.
Creatures can safely move across the ice sheet at their encounter speed. Creatures moving across the sheet at their combat speed must make a proficiency throw of 2+ each round or fall prone. Creatures moving across the sheet at their running speed must make a proficiency throw each round with a target value equal to their encumbrance or fall prone.
The ice sheet can support a maximum weight of 75,000 lbs. across its entire surface. Any additional weight will cause the ice sheet to sink below the surface of the water. In addition, heavy creatures might break through the ice beneath their feet. A 1” thick sheet can only support small creatures (less than 35 lbs.). A 4” thick sheet can support man-sized creatures (up to 400 lbs.). A 1’ thick sheet can support large creatures (up to 2,000 lbs.). A 10’ thick sheet can support gigantic creatures (up to 32,000 lbs.). For each size category by which a creature exceeds the ice sheet’s limit, the ice has a 1 in 6 chance each round of breaking beneath their feet. When this occurs, the creature falls into the water. Creatures in icy water also suffer 1 point of cold damage per round and must make a swimming check or begin drowning. If the creature passes the swimming check, it may pull itself back onto the safety of the ice on its initiative (although the ice may break again).
The ice sheet is only as resilient as any other large block of frozen water. It counts as a structure with AC 2 and 1 shp per 20 cubic foot area. Man-sized creatures, large creatures, and light ballista cannot deal damage to the ice floe. Huge creatures, non-magical fire, and magic can deal 1/5th damage. Artillery, gigantic creatures, and magical fire can deal full damage.
Once created an ice sheet is perpetual until dispelled. Counterspell or dispel magic will instantly melt an ice sheet in above-freezing temperatures. Otherwise, when the spell expires or is dispelled, it does not melt until temperatures rise. (That is to say, the ice doesn’t magically heat up!)