The Soul Stones harness ability is a bit overblown given the massive set-up cost, but it's all gravy on a massive upgrade to Charcoal Diamond, and an indication that the other colors will be getting some improved mana rocks soon enough, probably a few as early as Marvel Super Heroes next year
Remember any lands you tap to use Primal Adversary's ability will still be tapped even if you turn them into creatures, so choose wisely
Donquixote Doflamingo (OP01-060): One of the best Leaders in the early sets, Blue Doffy had multiple moments in the sun, with OP-09 being its peak
Once you get into the free rental programs, you can immediately start building and playing Commander decks that would cost hundreds of dollars in paper, competitive budget Modern / Pioneer decks, and much more
Because it would be mean to walk you this far through the mechanic's design and not show you a finished version, I present Cunning Bandit
A well-built deck with a smooth mana curve and a good mix of creatures and spells will function just fine, even if it doesn't have much synergy
