This is a short tactical disscusion on the benefits and drawbacks of the oft underestimated Tyranid Ripper Swarm.

Rippers are, in my opinion, the unit that is the most 'Tyranid-ish' of all the Tyranid units. After all, Tyranid's whole fluff points to an endless swarm of critters that never end. For this reason alone, I love to take at least one brood in my games, just for the effect.

Anyway, Rippers are designed for one purpose, and one purpose alone - To tie up ememy units so that they can't bother the rest of your army. Without several bio-upgrades, they are not very good at actually killing anything. At first, this seems like a complete waste of points. What's the point of having a unit that won't kill its worth in points, right? Wrong! Rippers are a support unit, designed to give the other Tyranid units a chance to survive longer and kill more since they are not getting shot at/charged by the unit that the rippers are attacking. Ripper Swarms of 3 or 4 bases can tie up a dangerous squad for 3-4 turns easily, leaving you the option to charge in with your Genestealers, Raveners, or whatever later.

The best targets for Rippers are usually large squads of infantry, small heavy weapon squads, HQ squads, or anything that you don't want bothering you for a few turns. For example, say there is a devestator squad with 4 heavy bolters in it blasting away at your army. Normally, heavy bolters do serious damage to Tyranid armies. However, tie them up with Rippers, and they won't be firing a shot.

Rippers are actually surprisingly versitile, due to the fact that they can be used either as a Troop choice or (given wings) as a Fast Attack choice. However, an upgrade that I would always recommend is either Wings or Leaping. Without Fleet of Claw, your basic Rippers are simply slow. Arm them with wings (get it! ARM them with WINGS... ok, never mind) and they will be able to tie up anything on the board very quickly.

One final thought - use Rippers with care. Avoid blasts and STR 6 weapons, as these will decimate Ripper squads.