If the skeletons of your death vocalist are in Diablo 3 have been weakening for a few days, then it could be because Blizzard is using the Phylactery "Gebeinglocke" disabled.
As the American community manager Tyvalir announced, the bell has been deactivated for the time being. Once the bug has been investigated and the problem has been resolved, activation will be announced in the forum.
Now there are those too translated message of the German Diablo 3 team:
We are currently investigating reports that there is an issue with the legendary feature of Gebeinglocke. We have therefore disabled this feature for the time being until we can prepare a hotfix to fix the problem. We will update this post as soon as it does.
Special thanks to the players who made us aware of the problem and thank you for your patience while we work on the fix. "
Diablo 3 - Necromancer Exploit
The cause of it all is a bug where you get the bonus of Bells could pile up endlessly outside the great nephale importals.
In short: you start that great nephala importer, teleported to the royal crypts and used Command skeletons on the pillars. Then you teleport back and go into the large nephale import portal. Diablo 3 thinks that your skeletons continue to attack the pillar and grants you the constantly increasing bonus effect of the bells.
Combined with the Necromancer passive Forbidden creation the large nephale importer is child's play. As long as you don't use Command Skeletons anymore, the effect remains.
With this exploit, players also have large nephala imports with them Level 130-140 packed. Of course, taking advantage of such errors is prohibited by Blizzard. Since it is also relatively easy to identify its usage, some people can probably rely on it blocked accounts "looking forward".