Seven mana does put this card on the backfoot for competitive viability, but Sin can be a rather serious Commander or reanimator target
With plenty of huge, expensive, and threatening dinos to choose from, were practically spoilt for choice
Kinnan, Bonder Prodigy takes a different approach than the 3 previous entries, electing to instead turbocharge your mana dorks, mana rocks, and any other nonland permanent you control that makes mana by enabling them to produce an additional mana of any type they produce
Im afraid this will end up a clunker, but its one of the splashier cards in Avatar: The Last Airbender
The cEDH approach uses Rograkh as an easily-accessible piece of sac fodder for partner Tevesh Szat, Doom of Fools or a ritual like Culling the Weak