Grim Reaper Eddie - Awakened Death grip bug(?)

According to the spell description:
... prevent all enemies from healing until they die...
So my question/ bug report is: Is it supposed to just inflict heal block or is it an innate effect?
I have not seen it inflict heal block to any toon so far. And anyway red heal block is kinda useless.
Neither have I seen it stop enemies from healing after numerous tries. It could be a good moonchild with vampire cosmic counter if it worked properly.
So, devs, which one is it supposed to do?