Youre unlikely to run out cards playing Black
Making all stolen creatures into Pirates doesnt need to become a big part of your deck, but it is potentially a very interesting theme to blend into a list given how many strong Commander cards refer to that type
Watermark: Planeswalker DailyMTG Story Spotlight Illustrated by Daarken Standard Not Legal Alchemy Not Legal Pioneer Legal Historic Legal Modern Legal Brawl Banned Legacy Legal Comp
What to watch for: If you want factory workflow customization (custom backs for every card, complex packaging options, etc.), MPC-style printing still gives more knobs
Absolute Virtue Absolute Virtue is way expensive, but let you accept any and all damage, so it's a waste of an attack for your opponents as long as you control this card
Im most exciting about a card that benefits from a mill strategy but doesnt demand one: Drown in the Loch, a flexible and powerful spell, assuming you can guarantee your opponent has five or more cards in their graveyard