The Saving throw option is doable with Group Check and Damage. It's built for working on groups, but nothing in the code precludes you from having a group of 1. I'm not sure about the AC option, though. Token-mod can apply damage to a token, and ChatSetAttr can change values on a sheet, and an attribute lookup can find values, but I think you'd need a custom script to put in the conditional of "Here is my attack, IF I hit, THEN apply damage to target." I don't think such an animal exists. Maybe PowerCards?