One of the DH clones has Impale / Ricochet.
One of the Crusader clones has Blessed Shield / Shattering Throw.
All of the Necromancer clones have Bone Spear (various runes).
If these are reflected back to the heroes, they’re going to cause deaths. Oddly enough, this possibility was brought up as soon as the PTR blog was published, and queried whether it could happen precisely because it would be ruinous for hardcore heroes.