I too would like to express my sadness over Dad_Scaper stepping down. His discerning eye has been a great benefit to the SoV project, and his direct and sometimes blunt evaluations served a valuable role. D_S, you will be missed.
Which means it's time to step up and start doing my job. I have been doing quite a bit of playtesting and am ready to place some votes, I just need to sit down and do the write-ups.
Rat Swarms by Killometer
How well do swams of pint-sized rats do in Heroscape?
Balance
It is somewhat difficult to theoryscape exact pricing on this unit, as common squads with similar attack/defense stats either have range or bonding. The Rat Swarms have a combination of good speed due to Scramble and Disengage and a special attack that each figure of the unit can use independently, but rather weak stats otherwise. Fifty points is at least in the ballpark. For more details on this point see the Playability section.
Theme
Treating swarms of tiny figures as a single combat unit is fairly common in fantasy games. Making them mobile is a perfect fit, as is the (to your opponent) mostly annoying but sometimes troublesome Ravenous Swarm Special Attack. Initially I was put off by the figure choice because 1) I do not like common squads where all the member use the same scuplt and 2) it is so darn tiny. But when I got the figures they were not as much of a problem as I expected. They are easy enough to see on the battlefield and, due to the nature of the figure, the sculpts would end up looking pretty much the same even if they were different. Calling them Height 2 is a stretch, but it is necessary for gameplay.
Creativity
Using a swarm as a single creature is fairly common in other fantasy games but has yet to appear in Heroscape. The powers are creatively designed to give the feel of a unit that is quick and annoying and not overpowering.
Accessibility
The painted version of the miniature is fairly hard to come by; only 13 right now on abprices. However this miniature comes with the Castle Ravenloft game, and Auggie's is selling the minis individually. With 110 in stock right now and Castle Ravenloft still in print I am ok with the availability.
Playability
The Rat Swarms are quite speedy. Scramble 2 ends up feeling somewhat like Flying, allowing them to zip around ignoring small terrain changes. I found this especially effective in the River of Blood scenario where regular Flying is restricted. Disengage is also very helpful in being able to hunt down the figures you want to kill instead of getting locked down by screening units.
While they do get into the action quickly, unfortunately they do not do much when they get there. Each unit being able to do a special attack is certainly valuable, however their special attack isn't potent. Against a single opponent 1 attack of 3 is almost always better than 3 attacks of 1, except against a handful of special units. It's the same reason Q9 usually attacks with 3 dice each attack; concentrating your dice into a single attack increases the odds of punching through the opponent's defense. If Rat Swarms could attack multiple figures with Ravenous Swarm it might be different, but as-is it's generally weaker than single special attack of 3. Defensively two defense dice on a melee unit doesn't stop much (as Macdirk players can attest to), but their tiny size does help them hide behind obstacles better than most.
After a while of playing against the Rat Swarms I started mostly ignoring them. If they tied up my figures I would attack (and usually kill) them, otherwise I would just wait for them to come to me while I concentrated on killing units that would give me more trouble.
As a Deathreaver counterdraft I found the Rat Swarms disappointing. Even though Ravenous Swarm prevented the Deathreavers from using Scatter, it usually did not have enough punch to kill them. The Swarms fared better against Goblin Cutters, but even then the Cutters put up quite a fight due to larger numbers and four attacks per turn. As a screening unit they did not do much due to their lack of defense, and their defense hurt their usage as glyph-holders. When used as assassins that zip through enemy lines and hunt down range units or other key figures, they lacked the offense to get the kills and were quickly killed themselves in the ensuing counterattack.
Bottom line, I found the Rat Swarms to be ineffective. This isn't something I feel that simply lowering the price would fix; even if they were cheaper they would still be an ineffective use of an order marker, though they may have some value as cheap filler. I really think that what the unit needs is a fourth squad member, to give them more attacks per order marker and more bodies on the field.
Summary
The Rat Swarms have a distintive feel that matches the theme well. They are quick and annoying, zipping into enemy territory and nipping at heals. I really wanted to like them, but I continually found them disappointing. They have neither the offense to get kills or the defense to survive on the field; in most of the games I played they were just a road bump for the opponent to get over. I certainly do not require tournament-worthiness, but as they are they have little effect in any game they are in. I waffled back and forth on how I wanted to vote, but in the end I leaned against.
I vote
for the Rat Swarms.