mtg are showcase cards legal Enlightened Tutor (showcase) reveal it Fierce Guardianship Showcase P Avatar:

Belakor doesnt help you ramp to your demons, but it does give you a massive wincon in the command zone, and being a Grixis commander gives you access to blue, which means you can use some of the cheaper, powerful blue-touching demons from 40k like Exalted Flamer of Tzeentch

While Prosper and Rocco benefit from Junk, it doesnt seem that any commander benefits from exile play in this set

It might be worthwhile if you ignore the potential token and just go for cheating the equip cost with Sigarda's Aid or something

Are you attacking

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Have a few ways to mass-mill your library, such as Hermit Druid or many of the cards in Innistrad block