As two actions, you create a wall of ice twice as big as normal at a point within 20 meters that lasts for the duration. The wall can’t occupy the same space as a creature or object and doesn’t need to be vertical, though it needs a firm foundation.
If a creature would be surrounded on all sides by the wall (or the wall and another solid surface), that creature can make a Reflex saving throw.
On a success, it can use its reaction to move up to its speed so that it is no longer enclosed by the wall.
The wall is an object made of ice that blocks line of sight. The wall can be damaged and thus breached. It has 12 Defense, 2 Soak, and 1.5 Health per centimeter of thickness, and it is vulnerable to fire damage. Reducing a panel to 0 health destroys it and might cause connected panels to collapse at the GM’s discretion. When destroyed, it leaves behind a sheet of frigid air in the space the wall occupied. A creature moving through the sheet of frigid air for the first time on a turn must make a Fortitude saving throw.
On a failure, it takes 5d8 cold damage and is slowed 1 until the end of its next turn.
On a critical failure, it takes twice as much damage and is slowed 2 until the end of its next turn.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
You can use this spell to bridge a chasm or create a ramp. If you create a span greater than 4 meters in length, you must halve the size of each panel to create supports. You can crudely shape the wall to create crenellations, battlements, and so on.
If you maintain your concentration on this spell for its whole duration, the wall becomes permanent and can’t be dispelled. Otherwise, the wall disappears when the spell ends.
You can increase the damage by 3d8 for each additional mana expended.