Di Tian thought about it and concluded that there probably was an unknown side effect to cultivating the Acheron Nether Art that he did not know of at the moment. It was either that, or perhaps there was a mutation possibility of the Qi from the Acheron Nether Art reacting with his unique constitution.
Because of this, Di Tian was hesitant about letting the energy influx from Fang Ao continue just like that. But an impulse reminded him that he could just wield the unique qi directly instead of allowing it integrate with his body, and that's what he did.
As if on cue, some fragmented insights on Fang Ao's application of the Death God Rule suddenly appeared in Di Tian's mind next.
Di Tian was rather surprised that the Taboo Imprint even had this function, but it didn't stop him from utilizing it.