Man, your use of acronymns is painful. I'm still not sure what 'WoS' is... wand of speed maybe?  An oddly formed sentence if so.

Anyhow, I completely agree with Shadow_Avenger that full fire is simply not the right build (in most case, especially against erebus).  Your big damage ability, circle of fire, is simply not relevant enough against someone with batswarm. Further more, he is calling all the shots, as he has the only source of stun OR slow.

Out in the open, you'll likely have a hard time either way, as he is a very strong solo DG. In a lane, though, you should be able to keep him somewhat surpressed with fireball, while switching to ice mode when you need to get in close.  If he goes for charm, try and deep freeze it. Either way, a solid nova/rain combo can help your burst damage a bit, while also limiting his options greater. (Slower attack AND slower move).

Totem of Revelation may helps cause then you can see Eberus before he can bat swarm into you and it only cost 50 so if it doesn't work for you can sell it and be out 10 gold.  Combine this with Fire Aura and then assuming he didn't take the Swift Anklet you can out run him so you can fight him on your owns terms and don't have to worry about him Ninjaing you.

Besides Bite the only other way Eberus deals damage is auto attack, until his minion arrive anyways. Sludge Slinger can help and it is cheap as well. Other annoying tricks the you can do with a fire TB is use all your abilities quickly and then use Orb of Defiance to give you time to have you skill cool down and do it again. Plus the 5 second of sitting around can give you time for you teamate to help out and give time for some of that bite slowness to go away. If you time it exactly right it can even be used as a Bite counter.

If he keep stunning you when you teleport then the boring solution is to carry around something that he can waste his charm on and then use the teleport scroll. Potion, Universal Gadgets, etc are good counters cause if he doesn't counter them you can keep fighting. When he start figuring out your tricking him then just use the teleport scroll first.