This is where the Night Lords come in to their own with one of their iconic signature units. These jet-pack marines are more than likely to be chosen by the Night Lords player in preference to the assault squads as they have some really nice options and abilities. Sadly, I just don't think they're worth the points cost - even though they fit in gloriously well with the Legion's play style.
As with other Night Lords units, we want the night raptors to be as large as possible to take advantage of the legions special rules. So go large or not at all -- this means at least 10 members, but 15 is entirely do-able if you're not thinking about deep-striking (with 15 members, the squad's footprint gets worryingly large). It gets rather pricey as well compared to regular Legion assault squads (and they're not troops either!). But they are fluffy!
The only negative thing here is no power fist for the Huntmaster. So, we've got to think about lightning claws, or power axes. The other choices for the unit are power weapons all around, and some special weapons to taste.
Here are a few build ideas.
Night Raptor Squad (10 members), 5 power axes, Huntmaster with artificer armour (410 points)
This is a squad to deep-strike in to play. Very expensive here, and strictly better to take terminators. But, this is Night Lords Raptors! Enjoy.
Night Raptor Squad (15 members), 3 melta guns, Huntmaster with artificer armour (405 points)
A kind-of tank hunting, base line squad. Out priced by other units that can do the job more effectively though.
Night Raptor Squad (15 members), 3 flamers, 5 power axes, 10 lightning claws, hunt master with artificer armour (590 points)
All kitted out. Seriously: not worth the points though. Uber coolness factor however!
Night Raptor Squad (5 members), all with pairs of lightning claws, Huntmaster with artificer armour (260 points)
This is a squad that ignores my above advice, but could potentially be built using the chaos space marine plastic raptors miniatures.