This isn't really related to Valkrionn's question, but what would people think about making blizzards not appear until the Deepening is created? That way, the blizzards don't start instantly when Liberation is completed.
They will still be spreading snow from Temples of the Hand, but at least that's only in their empire.
I've been planning to add an "Orb of Sucellus" event that happens after Liberation is completed, like the Godslayer event. The idea is that someone (i.e. Kylorin, if it's Kylorin who is in the Godslayer event) has collected the shards of the Orb of Sucellus and brought them to the most powerful nation on Erebus. They can be reforged by any arcane unit in any city with a Forge, or something like that.
Once reforged, the Orb of Sucellus would do something like:
a. Block Blizzards from moving into a 2-plot radius and destroy them if they try.
b. Give all Ice Demon units within the 2-plot radius the "Sucellus's Wrath" promotion, which gives them -20% or so combat and increased vulnerability to fire and nature damage. It would be auto-removed when the unit left the area around the Orb of Sucellus.
c. Give all Winterborn units another promotion, name not decided on, that does basically the same thing only it's not as powerful (only -10% strength, maybe even less, and less of an increase in vulnerability). It would be auto-removed when the unit left the area around the Orb of Sucellus as well.
However, that's more of a method to help fight the Frozen, not an unrelated benefit. You would be summoning the Frozen for the purpose of fighting the Frozen. So something else is needed.
I like the idea of Ice-Touched units. Out of all the ideas thus far, I feel it's the most appropriate with the lore of the Frozen.
Alternatively, I had an idea for a building which would be created by a unique Ice II spell (I had designed a unique set of spells for the Frozen, long ago, before discarding them), that randomly granted units built in a city with it the Unchanging promotion- which is what gives Taranis his city defense bonus but also makes him Held.
Maybe this building could be built in all cities on the map, but instead of randomly granting Unchanging units in the city can use a spell which will destroy the building but give them Unchanging.