Spell Ruling: Polymorph and Wild Shape

• Being polymorphed (or leaving polymorph) (or wild shape) does not remove any conditions. Conditions carry over. Unless the new form is immune to that condition. In which case the condition is removed. JeremyECrawford Tweet
• Certain spells will "kill" and not just cause damage. If this spell targets the polymorphed (or wild shape) creature (or PC), the creature (or PC) itself is killed if the combination of HP meets the criteria. Stack Exchange