I'm less of a fan of murdering winter due to the gem and research cost. On the other hand you do get it before flames from the sky and water doesn't have fantastic map spells anyway.
Earth attack fav assassin spell, just because it doesn't "couldn't find target" and attack caster.
Flames from the sky is nice, yet I always feel gyped when I cast it on a 300+ army and get 60 kills.
Mind hunt vs a non-astral nation is king
2 astral, good chance of killing an enemy. Spam it on an unprotected army and stop it in its tracks. Solo SC that's dominating but has no astral? Spam Mind hunt, even high MR will fall eventually. Love it... and hate it.