Missing sideboard cards? The full 15-card sideboard runs about $23.37.
Buy sideboard on ManapoolMono Green Landfall wants to flood the board with efficient threats like Mossborn Hydra and Icetill Explorer. Strategic Betrayal forces them to exile a creature of their choice along with their graveyard, so it is best early, when they have only one or two creatures, and it also denies graveyard value such as Esper Origins' flashback. Disruptive Stormbrood's Omen side destroys a creature with power 3 or less, hitting early Llanowar Elves or Sazh's Chocobo, while its Dragon side can later answer an artifact or enchantment like Earthbender Ascension or Sapling Nursery. Rapid Rescue and Deceit are cut since their marginal card selection and bounce effects are too slow against a deck that just wants to overwhelm the board with bodies.
Dimir Midrange relies on sticky value engines like Kaito, Bane of Nightmares, Enduring Curiosity, and Requiting Hex, so proactive hand disruption is key. Duress takes away their removal or Strategic Betrayal before it can be deployed, and Negate answers noncreature threats like Kaito or We Say Thee Nay!. Trim slower incidental-value spells like Rapid Rescue and Wistfulness that don't keep pace with their card advantage engines, and cut Awaken the Honored Dead since it is slow against a deck full of efficient interaction.
BRG is full of small, efficient creatures like Gene Pollinator, Greedy Freebooter, and Rottenmouth Viper, many of which cost 2 or less, making Requiting Hex and Witherbloom Charm's destroy mode clean, cheap answers. Disruptive Stormbrood's Omen side destroys a creature with power 3 or less, hitting early threats like Biotech Specialist or Umbral Collar Zealot, while its Dragon side later answers The Misty Mountains Cold. Rapid Rescue and Deceit are trimmed since this matchup rewards efficient removal over incidental card selection against a deck that wants to flood the board with cheap bodies.