With respect to the warband presented, it would be worthwhile to try and get more activations so that on the first round of engagement you can swoop the dragon in last and prevent a retaliation.

Of all the pieces in the warband, I think the Astral Stalker is doing the least for you.  I believe you'd get more out of a cheaper piece and increasing/upgrading fodder with bodyguards:

Elder Red Dragon
Skullcleave Warrior
Gnome Trickster
Free League Ranger (gives you CR3...)
Merchant Guard x2
Goblin Runner
Farmer

That gets you up to 8 activations at least.  An interesting strategy might be to use the Elder Red and Skullcleave to take out any enemies with area attacks while at least one Merchant Guard hides in the back.  You could then have the Gnome use his second invisibility on the Merchant Guard which would effectively give him conceal 11 against any sort of melee or ranged attacks when bodyguarding the dragon.

Although the stats for Bloodwar are not final yet, it seems that the Free League Ranger's "Zealous Follower" ability will also give the champion in question (the Elder Red, in this case) an additional use of his champion powers.  In this warband, it would mean another 50 VP for a total of 150 VP if you get the timing right (another incentive to use lower-cost creatures).

Until Bloodwar and Vintage play become legal, Gnome Trickster is not usable.Â

If I were to run an Elder Red Dragon warband, I might run something like this:

ERD 386
Eternal Blade 54
Orc Wardrummer 19
Fist of Moradin 12
x4 Merchant Guards 24
Farmer
Goblin Runner

500 pts, 10 acts

Maps: Hellspike, Evermelt, Magma Keep