“Living End is a cascade combo deck: it cycles creatures into its own graveyard, then casts Shardless Agent or Violent Outburst to cascade into Living End (mana value 0 and no mana cost, so it is cast through cascade; suspending it is a slow backup), which returns every cycled creature at once. Because cascade hits the first nonland card with mana value below 3, Living End must be the only such card in the deck: any sideboard card with mana value 0-2 (for example Inevitable Betrayal) may only come in by replacing Living End copies one-for-one, and Inevitable Betrayal is only worth that swap against decks whose best creatures are worth stealing (Eldrazi, big ramp threats), never against creature-light combo decks. The deck runs only about a dozen true lands, so Oliphaunt and Generous Ent are part of the mana base via landcycling as well as graveyard fodder, and Street Wraith is free cycling; none of these are "clunky top-end". Flexible slots to trim for sideboard cards are Force of Negation against creature decks (it only counters noncreature spells), Subtlety, Endurance, Wistfulness, Sink into Stupor, Colossal Skyturtle, Curator of Mysteries and one or two Waker of Waves; Mystical Dispute, Force of Vigor, Clarion Conqueror, Teferi, Time Raveler and Brotherhood's End all cost 3+ and are cascade-safe.”
Missing sideboard cards? The full 15-card sideboard runs about $61.95.
Buy sideboard on ManapoolThis matchup is a race against Urza's Saga, Eldrazi Temple, and big colorless threats, so Force of Negation is weak since it only hits noncreature spells and their real threats are creatures. Clarion Conqueror shuts off Basking Broodscale's adapt, Sowing Mycospawn's kicker trigger is cast-based so it's unaffected but their Spawn tokens' sac ability and Springleaf Drum both get locked out. Force of Vigor blows up Urza's Saga, Eldrazi Temple is a land so it's untouched, but the Saga and any Talisman/Vexing Bauble are prime targets. Teferi, Time Raveler taxes their instant-speed interaction like Dismember and Kozilek's Command to sorcery speed, buying crucial tempo for our combo turn.
Rakdos Delirium is a creature-heavy graveyard deck with cheap interaction like Lightning Bolt and Thoughtseize, so Force of Negation is weak here since it can't touch their creatures, making it a candidate to trim mentally but we're keeping it this round since their Thoughtseize and removal are still relevant targets; instead we bring in Force of Vigor to answer Nihil Spellbomb or any artifact threat, and it can be cast for free on their turn by exiling a green card from hand. Waker of Waves is a great blocker that shrinks their aggressive 1/1s and 2/2s like Stitcher's Supplier and Moonshadow via its -1/-0 effect, helping us stabilize while assembling the combo. Curator of Mysteries is too slow here, and Flare of Malice's sacrifice effect can take away a big creature without targeting it, so it doesn't earn its slot. Sink into Stupor's bounce mode is weak against a deck that doesn't mind replaying cheap threats.
Esper Control is loaded with blue spells (Teferi, Narset, Day's Undoing, Jace) so Mystical Dispute comes down as cheap as {U} to fight through their countermagic and disruption. Subtlety is weaker here since their threats are mostly removal spells and planeswalkers rather than creatures worth bouncing, so it's a reasonable cut alongside Curator of Mysteries which dies easily to Solitude or sweepers like Supreme Verdict and Wrath of the Skies. Our own Teferi, Time Raveler is excellent, shutting off their instant-speed Solitude, Orim's Chant, and countermagic while letting us cascade freely into our combo. Keep Force of Negation in since it's live against their noncreature spells like Day's Undoing and their own Teferi.