I made this Sideboard with the current meta in mind, so adjust it to your own meta. Keep in mind that in this deck, creatures are better than any other spell. This is why, for example,
Caustic Caterpillar is better here than
Gleeful Sabotage, because it can be reused with the assistance of
Tortured Existance
Spore Frog - Fog on a stick, great against decks that attack in for a lot of damage at one turn and go-wide strategies: Bogles, Heroic, Elves, Stompy, White Weenie, Izzet Blitz, Goblins, Burning Bush Zoo, Orzhov Extort, etc.
Gnaw to the Bone - Here against aggressive go-wide strategies: White Weenie, Goblins, Mono Blue Delver, Boros Monarch, Zombies, Stompy, Burning Bush Zoo, Orzhov Extort, etc. Flashback is great if we accidentally mill it.
Faerie Macabre - Uncounterable and recurable graveyard hate. Good against U/B control shells, the mirror match, other graveyard brews like BUG Morbid, etc. Also a flying blocker against Mono Blue Delver and Acid Trip.
Mesmeric Fiend - Great hand disruption against control, combo, and voltron builds, and against direct damage: Any control shell, Tron, Burn, Delver, Acid Trip, the mirror, Vinestorm, etc.
Caustic Caterpillar - Artifact and enchantment removal, also good against hate cards like Relic of Progenitus. Bring against: Affinity, Creatureless Control, Bogles, Heroic, the mirror, Turbo Fog, Acid Trip, Dimir Longbow, etc.
Wickerbough Elder - Great in all of the matches where Caustic Caterpillar shines, and a sizable blocker on the ground. Combos with Fume Spitter to create repetitive artifact and enchantment removal. Bring in against: All of the decks that Caustic Caterpillar is good against, and go-wide ground attackers like Goblins and Zoo.
Abyssal Gatekeeper - Another piece of removal against bigger creatures. Very handy against Tron, Bogles, Heroic etc.
Crypt Rats - Our trump card against swarm: Elves, Mono Blue Delver, Zombies, Goblins, Zoo, Boros Monarch, White Weenie, Stompy, Izzet Delver, Mono Black Control, Rebels, etc.
Entourage of Trest - Here against the Monarch strategies like Boros Monarch and Dimir Longbow, and also against grindy midrange match-ups and control for card advantage.
So that's it for the deck! Now before you go, let me give you a very important tip: when playing this deck, always keep at least one creature card in your hand, unless you have a dredger in your graveyard and you have the ability to dredge it. This lets you bring back an important creature in a pinch with Tortured Existance. Make sure to keep this in mind when playing!