To establish current value I looked at Ebay, TCGPlayer and StarCityGames and selected the lowest priced copy available, including shipping within the US
This basically allows you to turn everything on your board into mana, and Ashnods Altar is a key part of any kind of deck that likes killing off its own Creature for profit
Archenemy scenarios happen in near every Commander game, as one player gets too far ahead and the table unites against them briefly to bring them back down to Earth
Mindcrank In a format like Commander, where players are always gaining life and losing life for various reasons, Mindcrank sits on the board like a parasite, insidiously turning the regular moments of Commander gameplay into bonus mill
Three mana to Equip is steep enough, but five mana to cast really puts this out of reach for competitive formats