Long story short Ragavan is a house against any deck, is pure mana acceleration and card advantage, and packs them both together in a body that should cost way, way more than one mana
So What Made Dockside Extortionist So Good
This guy has a whopping 2000 defense, which is hard to overcome even in modern Yu-Gi-Oh
Emet-Selch, Ascian (Krrik, Son of Yawgmoth) When optimized to a cEDH level, K'rrik, Son of Yawgmoth can win as early as turn 1
Cavern of Souls is expensive, seeing as its a multiformat staple, but you should put it in your typal EDH decks if you have it
At minimum, this should include the card name and set, the edition (1st Edition, Unlimited, Shadowless), the condition assessment, the acquisition date and price, the storage location, and photographs of both front and back