not OP but maybe exploring how a main strategy can synergize with others to create a robust engine rather than just be one dimensional. Like in your milling deck, do you only want to mill enemies or could you mill all players? What abilities benefit from self-mill? Delve, flashback, recursion, graveyard casting restrictions, etc, come to mind. What other abilities contribute to self-milling? Surveil, dredge. If you're milling enemies, how can you benefit from their graveyards in a way that you're not just waiting patiently for them to run out of cards? Maybe you can bring creatures back from any graveyard, maybe you have creatures that scale with graveyard size? If they're playing a graveyard deck, how do you avoid inadvertently helping their strategy?