Reminder that before his final confrontation with Horus, the Emperor cast his compassion and other good traits into the warp so that he could face Horus without hesitation.
The reason for his decree to the Grey Knights is so that the "Shard" of himself that is on the throne can continue it's solemn duty while the "Shard" that could actually lead humanity is able to be reborn.
This is why the Terminus decree is how it is, to protect that "noble shard" similar to how Janus was created from being forced to remeld with the parts of himself that are on the Throne which would make him whole and powerful enough to implode on himself and ascend to godhood which he wants to avoid.
This also ties in with Valdor/King in Yellows work and goals, he is trying to find this shard of the Emperor in the Warp and his genetic experimentation is to create a blank that can act as a body for this shard of the Emperor.
This is also how GW plan to bring the Emperor back to the setting without facing the issue of him being overpowered.

>>529811009
i think you meant to reply to the post above mine
however i need them to stay the fuck away from devil may cry after the massive disappointment that 5 was to me personally