I havent tried this, but from what i experienced: when Grimward is made and monsters are feared, if you apply Decrepify to them, they immidiately swap to fear effect of Grimward. So I assume that the fear effect is RE-APPLIED every second or less. Cload of shadows is something like a curse I assume… Have played assassin like 1 hour total.
ya Cload of shadows acts like a curses. I forgot grimward is a totem made out of a corps.