Henzell wrote: Gives a shield with SH 3 + ICE_MAGIC/4 (SH 2 + ICE_MAGIC/6 in 0.5-) stacks with the shield from the helm card.
It gives you the benefits of a (not very good) shield without having to use up a hand to hold a shield. Does nothing if you are wearing a shield. Interestingly, does 2-14 damage to you per round if you have negative cold resistance, so don't do that!
The usefulness of the spell depends on shield skill, so you might want to use a real shield to victory dance up to level 1 at least.
Also: the shield evaporates whenever it's hit by any kind of fire attack, coming and going. Even zero damage fire spells. So every time you cast evaporate, poof goes your shield. Whether or not this is a problem depends on your play style.
Consensus is it's not a great spell, but it can help.