Effect: A storm of ice and freezing wind envelops the target, which takes 3d8 points of cold damage (Fortitude half). If the target fails its save, it is paralyzed and unconscious but does not need to eat or breathe while the ice lasts. The ice has 20 hit points; destroying the ice frees the creature, which is staggered for 1d4 rounds after being released. Whether or not the target’s saving throw is successful, it cannot be the target of this hex again for 1 day.
Ice Tomb (Su)
What is the range of ice tomb hex? Can it affect objects? Does the target need to drink? Can it affect a cold-immune creature? If the target succeeds at its save, is it still imprisoned? How long does it last?
Like most major hexes, the range is 60 feet.
In the second printing of Ultimate Magic, the text says, “A storm of ice and freezing wind envelops the creature…,” so it only affects creatures, not objects.
The target doesn’t need to eat, breathe, or drink.
The general assumption for effects is if the creature negates the damage from the effect, the creature isn’t subject to additional effects from that attack (such as DR negating the damage from a poisoned weapon, which means the creature isn’t subject to the poison). Therefore, a cold-immune creature takes no damage from the hex and can’t be imprisoned by it.
A target that succeeds at its save takes half damage and is not imprisoned.
Under temperate conditions, the ice lasts 1 minute per witch level. In tropical environments it might only last half as long. In cold environments where ice and snow persist without melting, it might last indefinitely.
Source(s) Ultimate Magic FAQ
Pathfinder Roleplaying Game Ultimate Magic. © 2011, Paizo Publishing, LLC; Authors: Jason Bulmahn, Tim Hitchcock, Colin McComb, Rob McCreary, Jason Nelson, Stephen Radney-MacFarland, Sean K Reynolds, Owen K.C. Stephens, and Russ Taylor.