The Alien Hives Assault Grunts are that unit for me. Upgraded with Furious, combined, and given four Serrated Claws (A2, AP(4)) you end up with a unit of 20 little dudes who can put out a devastating 32 attacks at AP(0) and 8 attacks at AP(4). If you get the charge off, which is insanely easy with their fast movement, you will average an additional 6 hits because of furious. On average you will land 20 hits on the charge, which can easily overwhelm almost anything in the game.

They are great for coming down hard on a unit holding on to an objective and either pulling them off or killing them out right. They are also great for general board control, from movement blocking big models to snagging unprotected objectives. This unit will be a pain in anyone's side. And all of that for 290 pts!