Last week we fough an encounter in Pyramid of Shadows that featured a couple of harpies. It was the first time I saw this level 6 controller monster in play: I had read their entry in the Monster Manual, and had a pretty good idea of what they did - but I was not prepared for what came after. It's not that we suffered a brutal defeat. In fact, we eventually beat the encounter without significant loss of healing surges or daily powers. However, it took long. Harpies don't have a particularly high damage output, but they more than make up for it with tremendously efficient control. A single harpy can keep a whole party immobilized for most of an encounter, and if you're facing multiples like we did... well, you'll be lucky if you get to move at all. I don't think that is anywhere near reasonable performance, for a non-elite controller - so let's take a look at its stat block, and try to change it into something more appropiate.
She loves to be in control.
Before I start tearing the Harpy apart, I should make a confession: we didn't use the monster as written in the book, but a house ruled version. There is a pretty good reason for this, though: harpies are utterly unplayable, out of the box. Consider the following power, which is a harpy's main attack:
There are many things that are so wrong about the power, but for now, we'll just discuss the one that forced us to houserule it:
Close burst 10
This is an attack that affects everything in a 10 square radius. Yes, including allies. You could conceivably prepare an encounter where all the creatures were deaf, or could teleport at-will, or otherwise ignore the immobilization. Maybe you could make a team of purely ranged creatures where this wasn't such an annoyance for yourself, but most of the time, this cripples your team as much as the opposing one. Since the fight in our game was primarily composed of melee monsters, we agreed to treat the attack as "enemies only", for sanity's sake.
For reference, this is how powers in huge bursts are usually templated in order not to affect alies (taken from a White Dragon):
Once we have addressed the friendly fire issue, we are left with a power with a ridiculously large area that all but guarantees that the PCs will be immobilized for the whole encounter. On top of that, we find that the hit bonuses are way too high, 3 points above the average value of (3+lvl.) for attacks vs. NADs, which only exacerbates the problem. The free pulling, handy for the classic Harpy+Cliff combo, is just gravy. And, in case you are wondering, yes, the power is as devastating in play as it reads.
Declawing the Harpy
There are several things that need to be changed before we have a monster fit for balanced and fun play. First and foremost, the area needs to be removed. Not reduced, nor tweaked, but just done away with. Immobilization (save ends) is a strong enough effect when applied to a single target. Another important point would be to reduce the attack bonus to a level appropiate +9 vs Will. Likewise, the bonus for the harpy's third power, Deadly Screech, should be lowered to +9 vs Fortitude. This would be, for me, the bare minimum.
There are other, lesser concerns, such as the sustain effect having a slightly strange wording (it doesn't make any sense to reapply the immobilization), and the fact that harpies have a really hard time dealing damage. Other than the Deadly Screech rechargable power, their only offensive ability is their puny claw - but it makes little sense for the monster to have to engage their enemies to deal pitiful damage, after taking so much effort in getting them immobilized. Even in their original, absurdly overpowered version, an encounter composed of 5 harpies would take forever to bring down an adventurer.
With that in mind, this is how I'd rewrite the Harpy's Song and Screech powers:
This leaves the harpy as a well rounded controller, capable of locking down one or two enemies at once, and with a potent, limited use area attack. It also gets a decent damage output, so it now gets a credible shot at killing a PC without the help of a convenient pit. Finally, its abilities shouldn't be so redundant when in multiples, so an encounter made up entirely of harpies could actually be playable, if not fun.