One Talos is fine.
In a cleanse mission, you can put it in front row.
Pull it back, if you have first turn.
Against Nids, I've put the Talos in front row.
My oppenent got first turn and his winged Hive Tyrant
immediately charged the Talos, and the Talos killed
his favorite puppy in round 1.
Scourges equipped with splinter cannons are useful
against horde armies. I recommend to buy the box.
Instead of the darklances, take the splinter cannons
from the starting box if available. This gives you
5 Scourges w/ Splinter Cannons (x4), Splinter Rifle (x1).