You can play with more than one incarnation, and have to beat them all, so getting those rewards help you live on to fight more. And if it's the last one, the Qi and yin yang count for scoring. If you care to keep scores.
Hi, new to the game.
So if you beat the last incarnation (or the single one in the easy level), it's over? you don't have to deal with the rest of the ghosts? (those on board and those still to appear?)
If so, thematically I imagine that once the 'master' (Wu-Feng) is beaten all the other ghosts lose their powers and vanish... is that right?