Han Xuhan had reduced Mu Ran with several factors in mind. First of all, saving a protagonist tier character was the greatest deed one could have to their name in a cultivation story. Such acts of selfless kindness often became a deus ex machina to save their ass down the storyline.
Secondly, Mu Ran was an asset to his growth. The system was generating missions frequently around this 'guy'. How could Han Xuhan bear to let such a source of survival points die?
Thirdly, Mu Ran was his only available ally on the current battlefield. As long as Han Xuhan could revive him taking a little bit of risk, the focus of the enemies would shift from him to Mu Ran, the stronger of the duo.
Fourthly, if his rescue and revival plan didn't work, he could easily abandon Mu Ran. He had planted a few things in Mu Ran's pockets while carrying him off. Even Mu Ran's corpse could be used to surprise their enemies as long as he could activate the law fragments etched on those plants.
