For more power? They don’t need to know the details, Harald didnt.
I think with the motivation of "envy" he discussed most or all tenryuubito could be coaxed into it; their ideology is all "me me me i deserve it all" all hes gotta do is say "look how messed up it is that the humans are rebelling, dont you want the strength to put them in their place?" Not all scum are obedient, but the celestials basically seem designed to create petty jealous dickheads out of their children
We dont know exactly yet how it all works but there might be a difference in quality, same as with Shadows and Moriah.
Shamrocks shadow aint worth the same as a shadow of a random CD scrub such as Charlos...
Imu pointed out when Harald was willingly to obey the WG that such a rare fool is a gold mine that comes once in a lifetime.
And I dont think he was refering only to him being an Ancient Giant but also a Conqueror...
In all the lifespan, Imu seems to have managed to gather only a handful of such fools who are willing to obey(Elders+ Figarlands)...
Before the climax of WG war, Imu might get the opportunity to forge pacts with more CoC users that would make him significantly stronger than forging pacts with non-COC users which probably barely affects his power... At least, that's my guess.






