Thanks to Grimore



Ten Ton Hammer Sorcerer Class Specialist Grimore Valentine has produced
a list of bugs and issues for Sigil's development team:

10. Finishers

When a player is “too fast” on trying to cast
a finisher, the finishers will actually “gray out” and then will not be
castable. This happens most often with Mimic.

• href="http://vanguard.tentonhammer.com/index.php?module=ContentExpress&func=display&ceid=644">Read
  the full list here
  
• Keep your eyes on href="http://forums.tentonhammer.com/showthread.php?p=134916">the
  Sorcerer forum to look for Sigil responses or changes!