Mystical Dispute's discount never applies here since none of their spells are blue, but it still counters any spell unless they pay 3, which can be hard for them to pay when they tap out for a big Eldrazi like Devourer of Destiny, Emrakul, or Kozilek's Command. Fatal Push whiffs on their biggest threats (Emrakul, Devourer of Destiny, Sire of Seven Deaths) and only reaches Sowing Mycospawn when revolt is on, so it is weak here. Surgical Extraction can strip a key Urza's Saga-fetched artifact or a copy of Ancient Stirrings/Malevolent Rumble to slow their engine. Keep Leyline Binding in as your main interaction since it exiles any nonland permanent regardless of color, and keep Lightning Bolt in to handle their smaller creatures like Basking Broodscale.

This Gruul Eldrazi combo deck is almost entirely colorless/green with no blue spells, so Mystical Dispute mostly just counters-unless-they-pay-3, which is still relevant since they're often tapped out assembling the Basking Broodscale/Blade of the Bloodchief loop. Surgical Extraction can exile all three copies of Blade of the Bloodchief from hand, graveyard, and library once one has hit a graveyard, which is a huge blow to the combo since Urza's Saga and Ancient Stirrings can no longer find a Blade. Thoughtseize is weaker here than against other decks since taking the wrong piece still lets Urza's Saga or Ancient Stirrings dig for the other half, but it's still worth keeping Stubborn Denial and Lightning Bolt in: Stubborn Denial can only hit noncreature spells like Blade of the Bloodchief (it can't counter Basking Broodscale), while Lightning Bolt can kill Basking Broodscale or a Blade carrier before the loop goes infinite. Your existing Leyline Binding is a strong answer to Blade of the Bloodchief and should stay in. Fatal Push only hits creatures, so keep it for Basking Broodscale (mana value 2) and Eldrazi Spawn tokens rather than relying on it against Blade.

Izzet Prowess is a low-to-the-ground tempo deck full of cheap colorless/blue/red spells, and Consign to Memory is excellent at countering their colorless threats like Mishra's Bauble while its replicate mode can snipe multiple copies of their cheap spells in one turn. Mystical Dispute counters their blue spells like Expressive Iteration or Preordain for just {U} and anything else for 3, which they often cannot pay while also deploying their aggressive plan. Thoughtseize is weak since they are proactive and have little to take that matters once they're on their plan, and Stubborn Denial is a worse Consign to Memory here since it only taxes 1 and doesn't hit creature spells like Monastery Swiftspear. Keep Lightning Bolt and Fatal Push in to trade with their small creatures.