This Gruul deck combos off with Basking Broodscale and Kozilek's Command loops fueled by artifact lands and Urza's Saga, making Force of Vigor and Brotherhood's End premium answers that can strip their engine pieces or blow up a Saga before it makes a Construct. Sink into Stupor is too slow against their combo-oriented plan, so it's cut for proactive disruption. Endurance is valuable both as a cheap blocker against Glaring Fleshraker and to exile their graveyard if they're looping Devourer of Destiny or Malevolent Rumble triggers. Race with Living End while using your artifact hate to disrupt their engine rather than trying to grind since their late game outclasses yours.

Izzet Prowess is an extremely fast, low-curve aggro-tempo deck built around Monastery Swiftspear and Dragon's Rage Channeler, so Force of Negation pitching your hand is far too costly against a clock this quick — you need every card to stabilize or race. Mystical Dispute is live against their blue cantrips like Preordain and Expressive Iteration, and Brotherhood's End sweeps their small creatures if you fall behind on board. Endurance is fantastic both as a zero-mana blocker to stem the bleeding and to hate out their graveyard against Dragon's Rage Channeler delirium. Try to Living End into Endurance/Subtlety-heavy configurations that stabilize the board rather than durdling with slower disruption.

Affinity wants to assemble Urza's Saga and Mox Opal into a fast artifact-based board, so Force of Vigor is a premium answer that can two-for-one their Saga tokens, Engineered Explosives, or Arcbound Ravager. Mystical Dispute is at its best here since almost their entire deck is blue and/or artifacts, letting you counter their Metallic Rebuke or key threats for one mana. Trim your clunkier top-end cascade targets and one Sink into Stupor since Affinity plays a lower curve and you want to be proactive with Living End rather than durdling. Keep Endurance in as both a blocker and graveyard hate against Emry, Lurker of the Loch.