Assuming your minions can get anywhere near the enemy DG. You'll need to get them past any creeps, and also they'll need to catch up to him if he runs. Neither of these issues are easy to solve because DGs are faster than minions unless horribly slowed and Erebus doesnt have the creep clearing capabilities of the assassins.

Correction, Erebus doesn't have the creep clearing abilities of many generals either. Mist isn't exacly a solid investment short of curing venom, and his autoattack leaves a hell of a lot to be desired.

I was actually thinking of bat swarm. But I don't play Ere myself so I'm guessing you wouldn't use bats to clear creep...

Not unless I was either REALLY confident that I wouldn't need to use it for a while(and could afford that freaking huge mana cost), or there were enemies at my citadel.

Erebus' minions ARE his creep clearing abilities. mist isn't exactly good but at least it can keep you safe while Nightwalkers pop up out of dead guys and start clearing the area. only takes 1 point after all. 

what i really find though is that an Erebus that has already built up a minion army (6+ Nightwalkers and whichver idol summons he has) can bring alot of pain quickly. 

That is most certainly true. Plenty of people find that out the hard way against me. 'Oh, that enemy teleporting in shouldn't be too hard, I should be able to handle hi---OMGWTFGANGRAPE'

Erebus' best strength is easily teleporting in with a full army right on top of someone who doesn't know what he has coming.