I guess their assumption is anything cast right away will have Legendary Resistance used if the save is failed and the spell is sufficiently debilitating, so better to use Polymorph since it’s lower level but strong enough to warrant using LR.
Also if for whatever reason it does succeed, turning the bbeg into a chicken right as they begin monologuing is infinitely funnier than just disintigrating them.
I guess their assumption is anything cast right away will have Legendary Resistance used if the save is failed and the spell is sufficiently debilitating, so better to use Polymorph since it’s lower level but strong enough to warrant using LR.
Also if for whatever reason it does succeed, turning the bbeg into a chicken right as they begin monologuing is infinitely funnier than just disintigrating them.