This makes it mechanically beneficial for you to recreate the moment where he kills Aerith
Functionally, youre either exhausting summoned characters to quest and acquire lore, or to challenge and banish other characters (thus slowing down your opponent from questing)
Continuing the idea laid down by Midnight Pathlighter, Sun Quan makes our creatures effectively unblockable
As long as there is a creature in a graveyard that you would like to copy, getting to exile everybody elses graveyard at the same time is a wonderful upside
However, if youre looking to collect or play with the actual cards would you rather have a sealed box or a box that was potentially tampered with
But, all that being said, he's a massive threat that demands immediate removal and, if your opponent doesn't have it, will quickly close out a game