First of all, you need the game
The main reason why this card is so insanely powerful is that its incredibly easy to summon you dont have to tribute summon it like most powerful monsters
Cards from before Exodus don't have expansion symbols, so check out Gatherer to find out their rarity
In metagames where decks like Humans, Affinity, and Spirits are the best decks, I strongly recommend playing only three Dark Confidants
Marneus Calgar himself is the alternate MTG commander for the deck, but has become an order of magnitude more popular than the Imperium deck's main commander, Inquisitor Greyfax
The Enchantress archetype is a synergy-based archetype built around playing enchantments and leveraging the body of enchantments you cast to draw extra cards, generate incremental value, and eventually overwhelm opponents through attrition and inevitability