When you discord strike a hero, several talents benefit from this, like the level 1 attack speed talent and level 16 extra melee damage talent. But even when you hit a hero, if they are immune to silence, these extra benefits do not trigger. Seema a little buggy. Why should these benefits depend on the hero being silenced rather than just being hit as the talents state?
The AS bonus for Overwhelming Power and damage bonus of Lethal Onslaught don’t work if the target is Invulnerable as they aren’t being hit by Discord Strike.
There are a few such interactions in HotS, mostly bonuses not being triggered if the target is in Stasis or Invulnerable.