So the return match against Arsanil, Arnie-sil Arny something damn dragon thing anyway. I lost quite badly and I totally blame the big green nasty flappy thing. I did manage to kill the rider with dryads on a charge and it rolled the unbreakable result and stayed where it was but killed my dryads first and it was rather late in the game anyway. I have found that if I manage to charge the dragon it means its just eaten something that I didnt really want it to. My fault for not setting up the charges properly. But 20 inches and seeing over units gives it massive choices and influencing them is next to impossible. He also backed it up with shooting light cavalry as a nice distraction and Volands Venators. I chewed them up with an Alter and the 2 remaining Wild Riders with a war banner on each flank. It felt good but still wasnt enough points to win.
I think a dragon with some magicking deathstar units is very good against us as theres little we can do against either...

What kind of list are you running? My Wardancer Highborn w/ Bol, AoN and AP has been a huge asset against Dragon Riders. Something to think about. Even if you don't land that KB you have the AoN to hold him in place and can use your 4+ ward in alternating rounds.

If, and that's a big if, you can get the charge with wardancers, I always go with +1 attack on the charge, directed completely at the Dragon. St5 and re-rolling wounds will put a big dent in a dragon, which is important since you'll still have to contend with the Dragon once the rider is KBed.

Just some thoughts. with an idea of your list we can give more specific advice.

At the moment we are at about 1400-1500 points in a map campaign. So the points differ a little.

Alter noble
Singer, scroll and stave
2 x 11 GG
5 GR with musician
2x8 dryads
1 x8 Wardancers
3 treekin
a great eagle
5 wildriders with warbanner should be all up 1450 ish

This can be changed for next round as we only have to fit the points.

I'm sorry, I thought we were talking about Dragons and other "Big Nasties." @1500 are you even facing one?

Well its not one of the actual "Big Nasties" but it is a dragon and its smashing me up. I don't have lord options at this level but he's Dogs of War and they can get a Dragon.

Asranil himself only has 2 wounds so he is not too terrbile to knock off with Missile fire and a hail of doom. And its not a star dragon so a treeman with some support can also take out a dragon.

Using some of the units you listed. Try a WR noble who has the annoyance of Netlings in a unit of Wild riders with a warbanner. By locking Asranil and his dragon in a challenge you should win combat (he should do 1-2 wounds, while you have banner, rank, warbanner, and outnumber). If he does not break you can further pile on into his side in later turns (hopefully, keep challanging) to get a rear and or Flank Bonus.

Well I have beat Bloodthirsters and Dragons with EG Bunker with the Lord and Bsb.

1. By using hatred. Bloodthristers and DE Dragons both have it. I offer up a naked unit of Wild Riders to funnel them where the EG can get at the big nasty.

2. Give them the irresitable flank of your EG. They Kill some EG (5+ ward). Stubborn on a 9 with the reroll (96% chance to stay). Move the Lord over challange. He does 1 or none. Win by out#, Banner, War Banner, and Bsb.o 3 or 4. The key is you have to make sure the big nasty is the only thing that can engage.

Also and Archmage, with Glamorweave, steed, A.o.N, S.o.C.M, and Mage stuff. In Wild Riders f/c Warbanner. Give him the front and he will probably take it.

Make a compy army and totally avoid playing such thing. (until late rounds at a tourney)