eamon
Explorer
It was a while back. As I recall it was 3 Wraiths, a couple Blazing Skeletons, a Boneshard Skeleton, some regular skeletons, and a few Decrepit Skeletons. It was a pretty tough encounter vs 5 level 4 PCs but the STR cleric got to go first oddly enough. So the wraiths ended up spending a couple turns immobilized while the starlock burned them down pretty well. One wraith became quite annoying phasing in and out of the room and that was about it. They do take a while to kill and I guess I can see an encounter with many wraiths and mad wraiths being nasty though a clever party that isn't pressed for time should be able to work around it. That's the thing with mindless undead, just focus fire on a couple of them and if things aren't going as you want once those are down then pull back and regroup. Its not like the undead are going to adapt to your tactics or set up better defenses. I suspect this is why wraiths are as they are, they stand up well against those tactics. A party that insists on duking it out toe-to-toe with mindless undead until one side or the other drops, they need to learn better tactics.
The absence of mad wraiths really matters; that dazing aura is not a joke. There's not much room left to tactically maneuver with that around. I'm not sure wraiths count as "mindless", but in any case their tactics suggestions are that they like hit and run tactics (using phasing) and will retreat when bloodied until they regenerate enough hitpoints. That's impossible to stop when the party is dazed (hard enough to do otherwise). I'm pretty sure that the encounter makeup really mattered here. Skeletons don't have any particularly tactically tricky features for this (although the boneshard's bloodied+dead-burst-thingo is nasty). A few wraiths are focusable, 6 get really tricky because when a bloodied one backs off the rest aren't somehow terribly vulnerable due to it (also, for the wraiths really to work well, they want to weaken every significant damage dealer; that requires a certain number of them). The mad wraiths are the icing on the cake that make a coordinated response very hard.
So, I expect you wouldn't have had as much issues because only a few wraiths just don't expose their particular brand of synergy so well.