Of course, Ren Suo certainly hadn't ventured to guess.
"Rippling Spring Sounds" still had 55 seconds remaining.
Ren Suo had already used these last 55 seconds the previous night to summon the plump Priest Zhao Zili, thereby obtaining enough information to confirm his speculation.
Zhao Zili, on behalf of the Lord of Billion Brilliance, conveyed the answers from the Three Gods: they could indeed probe Destiny, but only if Zhao Zili herself could perceive the True Form of the Destiny Cards.
Since the Three Gods could do this, then the Collector and Devouring the Spirit of the World should also have no problem—the game version numbers all updating by 0.01 was the clearest possible hint.
That is to say, Ren Suo had to summon game characters "between Destinies."