I've been playing Dark Souls 3 recently and looking back on some of the fights I feel like I see 2 specific times DQXI subtly references it in boss fights.

The biggest connection is a boss Pontiff Sulyvahn who wields 2 swords, is undead, and creates a weaker clone of himself during the fight. Sounds a lot like Tyriant and his moveset sometimes, not to mention they both use dark attacks.

Then when looking at the functions of Mordegon on phase 2 this is similar to the Twin Princes fight. One starts casting magic from afar before joining the true fight, and when you eventually kill one of them the other attempts a resurrection.

I know they are loose connections and the second one is very speculative but I cant help but think this is actually true to an extent.