When Hel was first released, her Special Abililty, Crush of Hel would lock out enemy heroes even when their special bar was full.
This was patched now a hero with a full bar can still use their ability when under the effects of Hel’s attack.
If Crush of Hel is used on an enemy Hero, and then Li Xiu’s Slash of Seven Blades, the enemy Hero’s special bar will not decrease at all. It is as if Crush of Hel locked it in place. This bug does not occur to heroes with partial special bars, only ones at full.
See screen shot below, Enemy Tiburtus is still full.