Read about the concept of Viparita Raja yog here
Phaladeepika describes about Harsa yog as below.
Definition
“If the 6th house or its lord is associated with or aspected by malefics or the lord of the 6th occupies an evil house (8th, 12th), Harsa Yog is formed.”
Description
“One born in such a yog is endowed with happiness, enjoyment, good luck and a stout body. He overpowers his enemies easily and is afraid to commit sinful acts. He is a friends to illustrious and prominent people. He is blessed with wealth, splendour, fame, friends, and sons.”
Notes
The underlying concept of Viparita Raja Yog given in Uttara Kalamrita (Refer here) aligns with this Yog of Phaladeepika.
Where basics, of Dussthana lord placed in other (or same) Dussthana house gives favourable effects and end results, is kept under light.
Sarala Yog - Viparita Raja yog by 8th house and its lord
Vimala Yog - Viparita Raja yog by 12th house and its lord