Killing black dragons/ dragons with no loss
 

I heard that you can trap them and they like attacking double stacks.

What makes for a good anti dragon army though.

I got hunters, scope +2 morale for them - does there 150% damage vs beasts count against dragons?

I'm thinking trap + dragon arrows turn 1 would work well.

Any suggestions on what to get to go 1st ? or do I need get the init bonus at the end of the warrior tree ? (otherwise trap obviously won't work.)

Yep onslaught, or females with angas ruby are required, also lina ice thorns placed correctly are very useful. If u place it good blackies will not attack units behind them.