perfectly preserved wooly mammoth corpses can be found in the permafrost of the Siberian tundra. Antarctic ice cores have provided insight into the earth's climate over the last 740,000 years. Cold can be a great destroyer: the "Little Ice Age" of 1250-1850 CE killed millions through famine and disease. But it is also a great preserver, protecting those it embraces from decay. Both these qualities, and more, can be found in the Ice-Rune, Isa.
While it is frequently identified with stasis, Isa is far from inert. Glaciers move slowly but they can wear down mountains and carry boulders and trees as if they were pebbles and twigs. Isa does not have to move quickly: it is inexorable as an oncoming ice age. It knows that sooner or later our fires must die and our green lands must succumb to the frost.
Isa's sense of time and place is very different than our own: there is something Lovecraftian about its enormity and its immense age. Where we measure in days and moments, Isa contemplates aeons. If things are moving too quickly for our liking, Isa can provide us with a respite. It can cool heated tempers and help bring calm to potentially explosive situations. It can also provide us with a broader perspective: that which seems important at this moment may be of little consequence in the context of geologic eras. Isa can provide a sharp, cold focus which will serve you well in combat (metaphorical or actual). It can help you to be in the moment without being of the moment, to rise above the petty distractions and concentrate on that which is eternal.
Like water, ice takes the shape of its container: Isa's flexibility allows it to work well in many different bindrunes. Combined with a faster-moving rune like Uruz or Hagalaz, Isa can become a devouring avalanche. Formed into a bindrune with Othila, it can become an impenetrable defense which protects you and yours from your enemies. (Consider how the brutal Russian winters repelled the forces of Napoleon and Hitler or how the snowy passes of the Hindu Kush have helped make Afghanistan the "Graveyard of Empires"). Combined with a healing rune like Berkana Isa can help still fevers and slow the progress of infections or cancers: bound with Ear it can sap the target's vitality and bring on the chill of the grave.
Isa is often used to block an opponent's way. Yet it can also be used to remove obstacles .Ice expands as it freeze: it can seep between cracks and shatter granite. Combined with Laguz and Thurisaz, Isa can become an irresistible force that will send the thickest walls tumbling down. The Water-Rune makes its way into the smallest chinks and crevices: the Ice-rune then expands and the Thorn breaks down the barrier. Isa can also be used to distract your pursuers and make their path slippery, or combined with Sowilo to turn illumination into snow-blindness.
And Isa's ability to preserve can be used to cement the gains achieved with other runes whose effect can be more fleeting. Combined with Ansuz, it might ensure that your words were remembered long after they were spoken. But this should be done with caution: that which is frozen often loses its vitality even though it does not decay. Isa can stave off corruption but it cannot give life to that which is dead. Although it may seem a timeless rune of eternal winter, Isa is tied to the cycle of the seasons. While the frost must have its season, so too must the thaw.