I have noticed recently that the deadly shadow cloak (maskeraith cloak ultimate) is bugged.
If you're in the middle of a charge attack animation as the attack damage/speed boost from the cloak expires you will deal a second round of damage of said charge attack.
You can see a demonstration of this bug in this video:( http://www.youtube.com/watch?v=87Q12F_L6mc )
Video courtesy: Enfeebler