I love the idea of the wraiths, and use them quite frequently out of personal preference, but are they really good enough to include in a squad?

They are the fastest non-dragon unit for waiqar, but at the same time their heroic doesn't work very often with only two dice, which leaves them at kind of a weird point. Good at everything, without being good at anything. Also I think wraiths prove just how overpowered the Riverwatch Riders are.

They roll only two dice, this is true, but also force attackers to roll one less die, unless they are casters. So, their defense is certainly top notch. Plus, they are a unit that's actually a great support unit: you don't want them in your first line, taking all the hits; you want them coming later, and targetting keypoint of the board. And their swapping ability is actually excellent to move away from specific locations units that are supported, or protected in other ways. Riverwatch Riders are great, but they are easier to use, so that in the end they look a lot stronger than wraiths

The issue is that I usually face Daqan, and so 3 battlemages is a common sight.

And the riders are downright OP, so I guess everything looks bad next to them.