Here's what I've got so far:
100 Gavriel
240 LADracoline - General, Pride Leader, Artifact*
100 Heraldor - HS artifact
120 Cleansing Phalanx
300 Dracoline
300 Dracoline
400 20x Sequitors
120 5x Sequitors
120 5x Sequitors (Battleline)
100 Ballista
100 Ballista
5 units on the board, 5 units in reserve (LAD, Dracolines, Dracolines, Gavriel, 20x Sequitors)
You can drop the battalion but it feels like it's too valuable given the core of this list already has Dracolines in it and you can take Sequitors as Battleline. You could drop the 20x Sequitors down to 5x, though.
You could swap the Heraldor for any 100pt hero, like a Relictor or Castellant. You could swap the Ballistas out but I think they work as a deployable gunline. It bothers me that I don't have a second mounted hero to give another trait from the battalion...
As for the artifact, there are a lot of great choices: Lens of Refraction, Mirrorshield, Aetherquartz Brooch (5+ refund CP), either of the Rend-3 artifacts, Gryph-feather Charm, Banshee Blade (synergy with +1 hit and -1bravery!), Ethereal Amulet, Mindlock Staff, Quicksilver Draught