Have you considered Nicol Bolas, the Ravager  ^Flip as the commander? You could probably cast him multiple times in a game compared to the original Bolas, which means multiple discards for each opponent. Reforge the Soul could be another good wheel spell for that purpose.

You probably need more ramp for the deck. Coalition Relic gives more mana than Commander's Sphere, and Thran Dynamo also produces a lot of mana for its cost.

Myojin of Night's Reach discards all your opponents' cards if you have 8 mana. Hypnotic Specter is a good early play to start the discard.

Not sure if you would be interested in Warped Devotion and more mass bounce spells like River's Rebuke.

Blatant Thievery is one of the best blue sorceries. Also a big fan of Sepulchral Primordial and Diluvian Primordial to steal the creatures and spells discarded.

Grave Betrayal could be better than Prince of Thralls since opponents can't pay life to bypass it. Thrilling Encore can act as a second Rise of the Dark Realms.

Phyrexian Arena could be good for more card draw.

Don't think you have enough fliers or Dragons to benefit from Dragon Tempest.

elgosu1337

While Nicol Bolas, the Ravager  ^Flip would be good as the commander, I feel like the deck is more built around Nicol Bolas. Reforge the Soul is also a good wheel affect.

I don't actually like Myojin of Night's Reach, it's expensive, and only does the discard once. Hypnotic Specter also seems like a strictly worse Dreamstealer.

Mass bounce isn't really something I'm interested in.

Blatant Thievery was in here, but was cut. Might come back in though. Diluvian Primordial was also in here, but I felt it could be replaced with some better cards.

I feel Grave Betrayal is on about the same level as Prince of Thralls. While they can get it back it comes at a cost, one that they can't pay forever. Although, Grave Betrayal isn't as weak to removal. Thrilling Encore is good, it's in another of the decks I've built. Totally forgot about it when it came to this deck though.

You underestimate Dragon Tempest, I don't need more dragons/fliers. The way the wording works makes it so Nicol Bolas does the ETB damage, making someone discard their hand. Bolas then also has the benefits of haste.

Thanks for the suggestions.