The mobility actually makes him quite formidable.  Instant mobility means you can take greater risks before being in the same danger another demigod would be.

An Erebus player can chase another demigod much deeper without being in danger than any other demigod can.  That kind of risk mitigation alone is very powerful, not to mention the fact that Erebus himself can take basically any other demigod in a stand-up fight.  The freedom to take more risks gives him a vast edge over other players.  Mist is another mitigation skill that's absolutely amazing, you can instantly drop any debuffs, instantly avoid any incoming nuke, and stay invulnerable for a fairly long to infinitely long period of time while your batswarm finishes cooling down.

No matter how you look at it, ridiculous escapability is an enormous advantage that can and does get exploited by superior players to translate into more offensive power.

I think the biggest problem of all the problems is the bite life transfer.

If it was say 1/2 (not dammage done, but life received to erebus), you'd be able to harm him.

Everything else can be dealt with, but 600 or even 775 heal + damage is alot to cut through when you factor in a life item stack, and priests.

Sssshhhhhhhhhh, stop telling l33t Sedna secrets. For once, I actually agree with something you said.

I would love to see your sedna build. Whatever skills you get, sedna will lose. What?? you said?? Erebus need heavy mana items??

When erebus bites (damage + heal) with less than 1000 mana, sedna have to use both heal and pounce. and eventually erebus will win.

Heal + Pounce mana ?? more than 1800 i guess??