Sylvan Elves versus Demons.

Well, in magic of light, you can simply take 3 Lords, although if you're planning to quickly capture a Utopia, you can also take Stormwind. It will also help against Creeping Horror if there are many flying units. Antimagic will help against Berserker (few people know that teleportation also helps against Berserker). Dispel will help against mind control. Seductresses have low initiative, so you can use the turn of the archers on them. In the battle itself, try to lock down the enemy so they can't reach you.
Regarding Utopias. If you have a hidden stash of Elves, you can simply take Elves (blue ones) and single Dryads (or double Dryads if you have Blessed Dryad Potion). In the battle, cast buffs on the archers.