Mono-Green Eldrazi wants to ramp into huge threats like Emrakul and Ulamog, so racing them before they stabilize is critical. Unholy Heat with delirium easily kills their early blockers like Fanatic of Rhonas or Disciple of Freyalise, keeping your clock alive. Consign to Memory provides key interaction against colorless spells like Sowing Mycospawn or Kozilek's Command as well as high-impact triggered abilities. Trim slow combat tricks for interaction that keeps their threats in check.

Boros Energy is an aggressive creature deck, and Unholy Heat is excellent removal here, easily killing Ragavan, Guide of Souls, or Ocelot Pride tokens, and reaching 6 damage off delirium to handle bigger threats like Ajani, Nacatl Pariah's Cat form. Spell Pierce can stop their Blood Moon, a devastating card against your fetch-heavy manabase, or counter key removal like Galvanic Discharge. This is a tempo mirror where both decks race, so prioritizing real removal over combat tricks that only help you attack is correct since you also need to defend against their aggression.

Affinity's board is stuffed with cheap artifacts and artifact creatures, making Meltdown a powerful sweeper that can wipe their Mishra's Baubles, Mox Opals, Welding Jars, and even Pinnacle Emissary at low X values. Unholy Heat kills Pinnacle Emissary outright once you hit delirium, and even the 2-damage mode picks off their small Drone tokens. While Tormod's Crypt can disrupt your graveyard, focus on proactive removal for their artifact creatures. Combat tricks are much weaker than sweepers and hard removal against a go-wide artifact deck.