Golgari Midrange has few relevant creature targets for Into the Flood Maw and its removal (Fatal Push, Abrupt Decay, Go for the Throat) is excellent against our threats, so we trim some of the bounce. Redcap Melee stays in the sideboard: it only deals 4 damage, so it can't kill Sheoldred, the Apocalypse (a 4/5), and every permanent Golgari plays is nonred, so each cast would also cost us a land. Disdainful Stroke answers Sheoldred, Culling Ritual, and Professor Dellian Fel before they resolve, since all three have mana value 4 or greater. We keep every Lightning Axe, because its 5 damage is enough to kill Sheoldred, which punishes our card draw plan, and discarding into a hand full of removal is fine.

Izzet Cauldron plays big bodies like Hearth Elemental (4/5), Eddymurk Crab (5/5), and Sunderflock (5/5) that Fiery Impulse can't handle. Lightning Axe's 5 damage does kill all three, so we leave all of our Axes in. Redcap Melee and Abrade stay in the sideboard: 4 and 3 damage don't kill any of those creatures, Redcap Melee would cost us a land since their permanents are blue, and Abrade's artifact mode has no mainboard targets. Disdainful Stroke counters Hearth Elemental, Eddymurk Crab, and Sunderflock, since all of them have mana value 4 or greater, but it can't hit cheap spells like Get Out. Into the Flood Maw is less appealing since bouncing a cheap Hearth Elemental just lets them recast it for less, but we still want some bounce for Sunderflock, so we trim only two copies.

UBR is a mirror-adjacent matchup full of blue spells, making Mystical Dispute a cheap, efficient counter against Make Disappear, Deduce, and their own countermagic. Disdainful Stroke snipes Indomitable Creativity, Atraxa, Grand Unifier, and Valgavoth, Terror Eater before they take over the game. Into the Flood Maw is weak since their best permanents (planeswalkers, Fable of the Mirror-Breaker transformed side) aren't great bounce targets and they can simply replay things. Lightning Axe gets trimmed since discarding cards to kill their small creatures is low value against a deck this grindy.