After playing with a Chanter for a while it became pretty obvious why they are so overpowered. In the first fight in the crossroads I summoned a phantom which was kind enough to stick around. Then the next fight I summoned three skeletons which also stayed with the party. I then sent them forward to spring the next attack and let them at it for a while to see how they did. After a couple of them fell I summoned some more skeletons thinking they would replace the skeletons already in the fight. By the end of that fight I had 9 skeletons working for me as well as the phantom as all the fallen undead got back to their feet. By the end of it I had a horde of 15 skeletons roaming around the area destroying everything they found.
Incredibly overpowered but a lot of fun.