"Popping mist and bat swarming costs mana. If erebus is a fair way into a fight, chances are he's pretty low on mana, quite often I've got enough for a finishing bite and that's it. "
Nope - by the time I am fairway into a fight I already have a pretty good idea if I'm going to win or not (usually with Bite I am). But if I'm not I can be sure I will have saved enough mana to bat swarm away.
"If he pop's mist and isn't behind his own lines, you can just wait for him to come out (it's a good time for you to pop a potion or a HoL) then gank him."
Sounds great in theory but I have NEVER seen this happen. Once mist is switched on my opponent has to move away or start taking damage. The opponent doesn't know when mist is going to stop so its very difficult for him to time when to start attacking again, particularly when there are a lot of minions around keeping him distracted.
"If he bat swarms and you've got any sort of range or speed to catch up to him he's most likely pretty helpless"
Making a BIG assumption there that you have the range or speed to catch me, and again that hardly ever happens.
"chris i anit a iddiot i wouldn't putt those up if they didn't work and bat swarm only gets u partly away and most of the times i play againist him aand her does it he is low aon health just chase him because u will have already lowered his movement speed"
This isn't even English.
Erebus is far and away the most survivable Deimgod. Forget bite for the moment, you are pretty much indestructable between bat swarm and mist.