Just had a tournament recent, was an absolutely great day! Although every list other than a rival Dawi army I played against had a dragon. Is there any efficient way in our list to deal with these things?
I don’t really see our Taurus units standing up to it and our war machines have seen some really heavy nerfs over all.
I will say I am rather disappointed with our little pdf book, majority of our units really got hit with the nerf bat.
I’ve yet to meet a bona fide dragon in the field. However in facing other scary models I’ve learnt:
Infernal Guard with Stubborn/Shieldwall make good sacrificial lambs. Hold the enemy there, stick them in a challenge treacle and await reinforcements. Aid their positioning with Steed of Shadows. Have them live longer with Daemonic enchantments.
Lammasu + Mantle of Stone + Healing Potion + Talisman of Protection is surprisingly durable. If your opponent is tooled up with magic stuff, they’ll have egg on face when they encounter its Sorcerous Miasma (invalidates magic weapons). Daemonic buffs as above.
These aren’t a silver bullet but could help slow down/survive combat versus a 700pt behemoth.
The most recent dragons I have faced is my friends chaos dragon w/ Bedazzling helm, 3 rerolls to gaze of the gods, Flail, shield and chaos dragon. I did this up for him for the tournament we played in, he’s a newer player and wanted a tough list
The second one I have faced is a high elf mage on dragon - obviously not as strong but the dragon carried that weight.
I do like the idea of the unkillable lamasu but worried about doom divers eating its face off as well. ahaha
Val from the Square Based Podcast vividly described how he dealt with Dragons in his games: Column of Crystal and Miasmic Mirage from the Illusion spell lore. Sadly we don’t have access to Illusion, but it shows that the best way is to not meet Dragons on their terms. Illusion is very capable of taking models out of the game completely, if that doesn’t work, I’d suggest feeding it cheap stuff so it doesn’t make its points back and kill everything else on the board 
black ork on wyvern fullplate, shield, dragonslayer sword, prot amulet
I would also say Blackorc on wyvern.
If you want to lower the enemys ward and Regeneration, just give him Daemonic familiar and power through his saves!
I run mine with a two handed weapon so he can deal also with high armour targets
Good call with the daemonic familiar. Lots of options for that guy.
Hey welcome to the forum, by the way 
Thank you!
The demonic familiar is such a brutal item. My brother plays ogres and he can’t stand that it affects his gut-star’s regeneration from the banner and oaken shield spell.
I think that might be the way to go though, Black Orc on Wyvern or give a Sorcerer prophet a chance with demonology to buff itself. The use of ash storm is such a strong spell. Could be good with bedazzling helm for -2 to hit him.
A case has been made for using an orc on a chariot instead of a wyvern cause 1) he gets impact hits, which may or may not be the only chance he’s got of doing damage 2) he’s immune to killing blow/monster slayer.
Kit one out with the daemonic familiar and maybe a set of obsidian vambraces. Cry Waaagh! and hope for the best