[MaxWilson]

If they were going for your choke point province, you could have cast Wolven Winter on the choke point and then hit them when they were inside of it. Pull your armies back out of the chokepoint when they're about to enter it, cast Wolven Winter; next turn, cast Murderous Winter while moving all your armies back into the chokepoint to intercept the enemy from moving out of the chokepoint. Maybe that's too risky, though, inviting defeat in detail; it also depends upon how much you mind losing all your PD in the chokepoint.

Another thing to do is to combine map-killer spells like Murderous Winter with a pre-casting of Leprosy. Normally you mostly only care about units killed, but if they're diseased the wounds persist. Nice synergy.

-Max