Harris understood that Trump is an obssesively vain, narcissistic man-child with no adult control instincts.
Prick his ego/pride (eg. crowd size & interest) and he'll lash out leaving himself wide open and vulnerable.
Harris further understood that beyond Trump's fearmongering and outrageous lies - the policy cupboard is empty.
Harris - with obvious intensive preparation - executed brilliantly against these 2 Trump vulnerabilities during tonight's debate. @KamalaHarrisWin