I also find it interesting that Shayd tends to hit and stun more often in HR when all other heroes have been killed. It seems with a full party of 5, her hit has been ~30% with a 40% stun. However, once the others have been killed, her rate moves to 50% hit with 50% stun. These numbers are only compiled from about 200 battles, and vary due in part to armor upgrades, but seem to be consistent. The numbers are also taken against the same target (primary boss, not henchmen) in HR.
KA