Mid Game+ magic.

[sushiboat]

If you lost a SC to Ermor AE, it's because relying on life drain items is a big mistake. (I thought you said in your first post that you had handled Ermor easily and were floudering after defeating Ermor.) You can't life drain from lifeless units, such as most AE undead. Most undead are also resistant to cold, so an Ice Devil isn't the best match (though it should do fine with the right equipment). Herald Lance and Charcoal Shield are good, or you can go with the double-handed Flambeau.

You shouldn't rely on a single set of equipment for a SC. You have to know the best equipment for the situation.

[shovah]

if you want something quite cheap vrs ermor then use (as said) a charcoal shield+herald lance on something flying(winged shoes on it if it cant fly)
golems are really good for this with their self buffs and something like jade armour will help get those buffs done quick.
and of course if he summons any big nasties or if you need an sc killer a golem with a gate cleaver is pretty good.
for any golem i would suggest ring of the warrior and a defence increasing item for misc slots