Well, definitely include the Dragon, I would include both trolls and the drummers. Then you should fill out that warband with gobos and that'll get you 550 pts. Then just include more warbands of goblin captains leading goblins. If you give the captains shields, each warband will be 100 pts each, so you can get 3 more full warbands. Then depending on what you give your dragon as upgrades (no matter what, either fly or tough hide) you'll have either 150, 100 or 50 more points to work with. If you give your dragon one upgrade, you can have a full extra warband so for exactly 1000 points, you can have:
Warband 1
Dragon (one upgrade)
2 trolls
drum
8 goblins
Warband 2-5
Goblin captain with shield
12 goblins with either shield, spear or bow.
That'll give you 60 models, and 11 might with 1 HEAVY hitter and 2 pretty heavy hitters. All your goblins will also have extra courage AND most of them will get to reroll their dice to win. You could always take out the drum and add another warband, but I find the drum to be more than worth taking, especially if it's the Gundabad one.
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