What's your basic strat with this list?
Beside the flyrant (and getting extremely lucky with genestealers), how do you plan to deal with armor? Stealers just aren't that good anymore, and gargoyles/gaunts can't do anything against
AV over 10.
What's the plan for the Broodlord? Going for any Psyker schools in particular? It's not a bad list, just a little confused, I think.
EIther way, it's a decent start. Just needs a little more direction,
imo.
A quick list at 1000, to keep with your horde motif:
HQ: Parasite of Mortrex (160)
Troops: Genestealer Brood - 10 'Stealers w/
AG; Broodlord w/
AG,
ST (235)
Troops: Hormagaunt Brood - 20 'Gaunts w/
AG TS (200)
Elite: Hive Guard Brood - 3 Hive Guard (150)
Fast: Gargoyle Brood - 25 Gargoyles w/
AG TS (200)
Leaves you 55 points to play with more models or different upgrades. Hive Guard are, essentially, the easiest anti-
AV to field for Tyranids, and they are great at any point value. Another really strong low-point unit is Termagants w/ Devourers. Ten points a piece, but definitely effective, especially in a spore. Of course, this would assume you had a parasite conversion and lots of ripper swarms. So avoiding that, you could throw in a Tyranid Prime without upgrades, along with a handful of warriors.
What models do you have available in your army?