Here is another entry in the fountain card ideas series.
(
http://www.screenshotdumpster.com/view/m7Gbd54856/elements_card)
(
http://www.screenshotdumpster.com/view/m7Gbd54860/elements_card22)
I personally think that immortal creatures/weapons are a bit overpowered, and this is an attempt at slowing down some of those creatures. This is not a shield, but a phase-shield-like permanent that lasts only three turns. The freeze would work in a manner similar to Ice Shield, with a chance to freeze all attacking creatures. It would give you more of a fighting chance against certain gods and especially immortal creatures.
I'm thinking that this could be used in conjunction with Ice Shield, effectively giving you a 30% then 30% chance of freezing (51% chance) for three turns. However, I'm thinking that multiple Ice Fountains in play for a given player would yield no additional benefit. I've also thought about making the upgraded card congeal instead of freeze...