Equinox research

[Marek14]

I tried to compile some notes that would allow to implement the Legends card Equinox. I read through the rulings and it seems the bulk of Equinox should be doable, but it would require some extra scripts for unusual spells.

First of all, even though the ability granted by Equinox can target any spell, it can only counter instants and sorceries, as no other card type can destroy a permanent upon resolution.
Since almost any permanent can be a land, we must take into account all possible spells.

Now, each permanent will need two values: Destructible and DestructibleNoRegeneration. Both are true by default.
DestructibleNoRegeneration is false in three situations:
1) the permanent has indestructible
2) the permanent has a permanent with Totem Armor attached
3) the permanent is affected by Pyramids.
Destructible is false if either DestructibleNoRegeneration is false or if
4) the permanent has a regeneration shield AND it's not prohibited from regeneration.

Equinox requires a destructible land (or destructible without regeneration for some effects). I am not 100% sure how it would interact with land that is simultaneously an Aura with totem armor, but I don't think it can actually happen since the only thing that can add land type to nonland things is Life and Limb and that only works on creatures.
Lands CAN be Equipment attached to a creature (for example any artifact land with Bludgeon Brawl).

So, the four main categories of spells affected by Equinox are:
1) Targeted destruction - Equinox will work if any of the currently legal targets of appropriate target group is destructible land you control.
Cards affected: any Arcane spell with Horobi's Whisper or Wear Away spliced, Abolish, Active Volcano (first mode), Aerial Predation, Aftershock, Allay, Ancient Grudge, Artisan's Sorrow, Asphyxiate, Assassin's Blade, Assassin's Strike, Assassinate, Aura Blast, Aura Mutation, Avalanche, Avenging Arrow, Bant Charm (first mode), Bash to Bits, Beast Within, Betrayal of Flesh (first mode or entwine), Blue Elemental Blast (second mode), Bone Splinters, Boom//Bust (Boom), Bramblecrush, Break Asunder, Builder's Bane, Chaos Charm (first mode), Chastise, Chill to the Bone, Choking Sands, Cinder Cloud, Clear, Clear a Path, Consign to Dust, Corpsehatch, Cradle to Grave, Crash, Craterize, Creeping Mold, Crosis's Charm (third mode), Crush, Crushing Vines (either mode), Cryoclasm, Cursebreak, Dark Betrayal, Dark Offering, Dark Withering, Dawn to Dusk (second mode or both modes), Death Stroke, Death's Caress, Deathmark, Decimate, Deconstruct, Demolish, Demystify, Desecrated Earth, Desecration Plague, Desert Twister, Despoil, Destroy the Evidence, Destructive Revelry, Devastate, Dimir Charm (second mode), Disembowel, Disenchant, Dismantle, Dismantling Blow, Divine Offering, Divine Verdict, Doom Blade, Drain the Well, Dreadbore, Dregs of Sorrow, Dwarven Landslide, Earth Rift, Eaten by Spiders (target), Echoing Calm (target), Echoing Ruin (target), Eightfold Maze, Emerald Charm (second mode), Esper Charm (first mode), Eyeblight's Ending, Feast of Blood, Feast of Dreams, Feast of Worms, Filigree Fracture, Fissure Vent, Flash Flood (first mode), Flesh Allergy, Flowstone Flood, Frantic Purification, Frenzied Tilling, Fumarole, Fury Charm (first mode), Ghostly Visit, Gleeful Sabotage, Glissa's Scorn, Gloomlance, Gloomwidow's Feast, Go for the Throat, Golgari Charm (second mode), Grisly Spectacle, Gyan Yu's 1,000-Li March, Hand of Death, Hearth Charm (first mode), Hero's Demise, Hero's Downfall, Hex, Hideous End, Hope Charm (third mode), Horobi's Whisper, Hull Breach, Human Frailty, Ice Storm, Icefall, Icequake, Illusion//Reality (Reality), Implode, Incendiary Command (only if third mode is included), Into the Maw of Hell, Just Fate, Kaervek's Purge, Kill Shot, Killing Glare, Krovikan Rot, Launch Party, Lava Flow, Lavaball Trap, Lay Waste, Leave No Trace (target), Liturgy of Blood, Maw of the Mire, Melt Terrain, Misery Charm (first mode), Misfortune's Gain, Mogg Salvage, Molten Frame, Molten Rain, Mortify, Murder, Murderous Cut, Mwonvuli Acid-Moss, Mystic Melting, Natural End, Naturalize, Nature's Claim, Neck Snap, Orim's Thunder, Orzhov Charm (second mode), Pain//Suffering (Suffering), Path of Peace, Peace and Quiet, Peak Eruption, Pthisis, Phyrexian Purge, Phyrexian Tribute, Pistus Strike, Pitfall Trap, Plummet, Plunder, Poison Arrow, Poison the Well, Premature Burial, Primitive Justice, Public Execution, Puncturing Light, Pure//Simple (Pure), Quiet Purity, Rack and Ruin, Radiant's Judgment, Rain of Rust, Rain of Salt, Rain of Tears, Rain of Thorns, Rakdos Charm (second mode), Rancid Earth, Ray of Dissolution, Ray of Distortion, Ray of Revelation, Raze, Reap and Sow (first mode or entwine), Rebuke, Reckless Spite, Red Elemental Blast (second mode), Reign of Chaos, Relic Crush, Rend Flesh, Rend Spirit, Ride Down, Rite of the Serpent, Rith's Charm (first mode), Roiling Terrain, Rolling Spoil, Rootgrapple, Saltblast, Scorch the Fields, Scorched Earth, Scrap, Seed Spark, Seismic Spike, Seize the Soul, Serene Offering, Shatter, Shattering Pulse, Shattering Spree, Sinkhole, Sip of Hemlock, Slaughter Pact, Slice in Twain, Slingbow Trap, Smash, Smash to Smithereens, Smelt, Smite, Smite the Monstrous, Solemn Offering, Soul Reap, Spiteful Blow, Spread the Sickness, Spring Cleaning (target - the clash part should be probably ignored even if top cards of all libraries happen to be revealed), Stomp and Howl, Stone Rain, Strangling Soot, Stream of Acid, Sultai Charm (first and second mode), Sunder from Within, Sundering Growth, Sundering Vitae, Survey the Wreckage, Swat, Tectonic Rift, Tel-Jilad Justice, Terashi's Grasp, Terashi's Verdict, Thermokarst, Treva's Charm (first mode), Trip Wire, Turn to Dust, Ultimate Price, Unforge, Urgent Exorcism, Vandalblast (not overloaded), Vanquish, Vanquish the Foul, Vengeance, Venomous Vines, Verdigris, Victim of Night, Victorious Destruction, Vindicate, Violent Ultimatum, Violet Pall, Volcanic Awakening, Volcanic Eruption, Volcanic Submersion, Wake of Destruction (target), Wallop, Wax//Wane (Wane), Wear//Tear, Wear Away, Weed Strangle, Wicked Pact, Wing Snare, Winter's Grasp, Wrecking Ball
Exceptions (cards that specifically destroy nonland permanents or that cannot be countered this way): Abrupt Decay, Krosan Grip, Maelstrom Pulse, Wreak Havoc
Cards that would only destroy Auras which is currently not possible for lands: Piety Charm (first mode)
2) Targeted destruction without regeneration - Equinox will work if any of the currently legal targets of appropriate target group is destructible/no regeneration land you control.
Cards affected: Afterlife, Agonizing Demise, Annihilate, Artifact Mutation, Befoul, Blastfire Bolt, Brainspoil, Broken Visage, Crosis's Charm (second mode), Cruel Revival, Crumble, Dark Banishing, Dead Ringers, Death Bomb, Death Mutation, Death Rattle, Detonate, Devour in Shadow, Execute, Expunge, Fatal Blow, Fatal Lore (second mode), Feast or Famine (second mode), Fissure, Flesh to Dust, Glyph of Reincarnation, Molder, Murderous Spoils, Oxidize, Pillage, Plague Spores, Polymorph, Pongify, Purge, Putrefy, Rapid Hybridization, Reprisal, Sever Soul, Slaughter, Slay, Smother, Snuff Out, Spite//Malice (Malice), Terminate, Terror, Tunnel, Vendetta, Word of Blasting
3) Global destruction - Equinox will work if any of the affected permanents is destructible land you control.
Cards affected: Acid Rain, Akroma's Vengeance, Anarchy, Armageddon, Austere Command (only selected modes are considered), Back to Nature, Boil, Boiling Seas, Boom//Bust (Bust), Calming Verse, Chain of Acid, Cleanfall, Cleanse, Cleansing Meditation, Consume the Meek, Creeping Corrosion, Crime//Punishment (Punishment), Culling Sun, Day of Judgment, Decree of Pain, Devastation, Eaten by Spiders (Equipment attached to target), Echoing Calm (nontargeted part), Echoing Ruin (nontargeted part), End Hostilities, Endemic Plague, Extinguish All Hope, Fated Retribution, Fight to the Death, Flashfires, Forced March, Fracturing Gust, From the Ashes, Hellfire, Hour of Reckoning, Hush, In Garruk's Wake, Leave No Trace (nontargeted part), Life's Finale, Mass Calcify, Meltdown, Mogg Infestation, Multani's Decree, Nature's Ruin, Overwhelming Forces, Paraselene, Patrician's Scorn, Phyrexian Rebirth, Primeval Light, Pulverize, Pure//Simple (Simple), Purify, Rain of Daggers, Ravages of War, Remove Enchantments, Retaliate, Return of the Nightstalkers, Reverent Silence, Righteous Fury, Ruination, Solar Tide, Soulscour, Stench of Evil, Strip Bare, Sunscour, Tempest of Light Tivadar's Crusade, Tranquil Domain, Tranquil Path, Tranquility, Tsunami, Turn to Slag, Vandalblast (overloaded), Virtue's Ruin, Wake of Destruction (nontargeted part), Whirlwind, Zombie Apocalypse
Exceptions (cards that specifically destroy nonland permanents or that cannot be countered): Gaze of Granite, Granulate, Maelstrom Pulse, Obliterate, Planar Cleansing, Supreme Verdict
Cards that would only destroy Auras which is currently not possible for lands: Serene Heart
4) Global destruction without regeneration - Equinox will work if any of the affected permanents is destructible/no regeneration land you control.
Cards affected: Damnation, Jokulhaups, Kirtar's Wrath, March of Souls, Perish, Plague Wind, Retribution of the Meek, Rout, Seeds of Innocence, Shatterstorm, Winds of Rath, Wrath of God

Special spells that would require considerations (please tell me if I interpret any of these wrong):
Burning of Xinye - Burning of Xinye can be countered through Equinox if you're either controller or target of Burning of Xinye and if you control less then 4 not-destructible lands. (If you control 4 or more, you could choose them and avoid destruction.)
Catastrophe - Catastrophe can be countered if you control a destructible/no regeneration land creature, since that would be countered no matter what the Catastrophe's controller would choose.
Cleansing - Cleansing can be countered in a VERY specific situation, when you control a destructible land and NO-ONE is able to pay life to Cleansing (because they are on 0 or less life or have Platinum Emperion or whatever).
Dark Temper - Dark Temper can be countered if the target is a destructible land you control and controller of Dark Temper controls a black permanent (can be affected by sleight effects and/or Swirl the Mists).
Divine Reckoning - Divine Reckoning can be countered if you control at least two destructible land creatures (so at least one would be destroyed whichever you'd choose).
Duneblast - Duneblast can be countered if you control at least two destructible land creatures (so at least one would be destroyed whatever the controller of Duneblast would choose).
Essence Filter - Essence Filter can be countered if you control at least one nonwhite destructible enchantment land (can be affected by sleight effects and/or Swirl the Mists) which would be destroyed regardless of the choice made.
Essence Vortex - Essence Vortex can be only countered if you, the controller of the descructible/no regeneration land target, can't pay the required amount of life.
Extinction - Extinction can only be countered if you control a land creature with all possible creature types (like animated Mutavault) which would be destroyed no matter what creature type would be chosen. Or if you happen to control land creatures with every possible type, which is not likely.
Eye Gouge - Eye Gouge can only be countered if the target is a destructible land creature with subtype Cyclops.
Ghastly Demise - Ghastly Demise can only be countered if the toughness of target is currently less than or equal to the number of cards in Ghastly Demise's controller's graveyard.
Grenzo's Rebuttal - Grenzo's Rebuttal can be countered if there's no way to choose an artifact, a creature and a land from among your permanents that doesn't include at least one destructible land.
Harsh Mercy - Harsh Mercy can only be countered if you control a destructible/no regeneration land creature with no creature types which would be destroyed regardless of creature types chosen.
Hydroblast - Hydroblast can only be countered in its second mode if the target is currently red (can be affected by sleight effects and/or Swirl the Mists)
Imperial Edict - Imperial Edict can only be countered if it targets you and ALL your creatures are also destructible lands so it will destroy a land no matter what you choose.
Inquisitor's Snare - Inquisitor's Snare can only be countered if the target is black or red (can be affected by sleight effects and/or Swirl the Mists)
Martial Coup - Martial Coup can be countered if you control a destructible land creature and X is 5 or more.
Overload - Overload can only be countered if the CMC of the target is 2 or less for unkicked Overload and 5 or less for kicked Overload (remember that with Life and Limb and changelings it's theoretically possible to have a land with CMC > 0)
Puppet's Verdict - Puppet's Verdict can only be countered if you control both a destructible land creature with power 2 or less AND a destructible land creature with power 3 or greater.
Pyroblast - Pyroblast can only be countered in its second mode if the target is currently blue (can be affected by sleight effects and/or Swirl the Mists).
Reign of Terror - Reign of Terror can only be countered if you control both a destructible/no regeneration green land creature and a destructible/no regeneration white land creature (can be affected with sleight effects and/or Swirl the Mists).
Rending Vines - Rending Vines can only be countered if the CMC of target is currently less than or equal to the number of cards in Rending Vines's controller's hand.
Soul Rend - Soul Rend can only be countered if the target is currently white (can be affected by sleight effects and/or Swirl the Mists).
Teferi's Response - Teferi's Response can only be countered if the target is an ability of a destructible land you control AND if the ability can be actually countered (I think there are currently no uncounterable abilities, though).
Toxic Stench - Toxic Stench can only be countered if its controller currently has seven or more cards in his graveyard.
Tsabo's Decree - Tsabo's Decree can only be countered if you control a land creature with all possible creature types (like animated Mutavault) which would be destroyed no matter what creature type would be chosen. Or if you happen to control land creatures with every possible type, which is not likely.
Twinstrike - Twinstrike can only be countered if its controller has no cards in hand.
Wild Swing - Wild Swing can only be countered if all current legal targets are destructible lands you control.
Wretched Banquet - Wretched Banquet can only be countered if no creature on the battlefield has lower power than the target.

It could be also argued that Equinox would only work if there's a SPECIFIC land that would be destroyed no matter what, and in that case many cards from this group would be completely immune to Equinox or they would have much stricted conditions. Specifically, Divine Reckoning, Duneblast and Puppet's Verdict would be completely immune and the following cards would have stricter conditions in addition to the previous.
Burning of Xinye: You control 4 or less lands.
Extinction: The corner case of multiple land creatures having all creature types as a group is removed.
Grenzo's Rebuttal: One of your lands would be chosen in any legal group (for example you only control 1 land).
Imperial Edict: You only control ONE creature and it's also a destructible land.
Reign of Terror: You control a destructible/no regeneration land creature that is both green and white (can be affected with sleight effects and/or Swirl the Mists).
Tsabo's Decree: The corner case of multiple land creatures having all creature types as a group is removed.
Wild Swing: Only ONE of its targets is currently legal.

Special spells that can't be countered through Equinox:
Bend or Break - it's possible (through not likely) that you'll put all your destructible lands in one pile and your opponent chooses the other, so there is always an outcome where Bend or Break won't destroy any of your lands
Breaking Point - since a player can choose damage, Breaking Point won't destroy anything reliably
Do or Die - it's possible that you'll put all your destructible/no regeneration land creatures in one pile and your opponent chooses the other, so there is always an outcome where Do or Die won't destroy any of your lands
Lava Blister - since you can always choose to take the damage, Lava Blister won't destroy anything reliably
Void - it's always possible to choose a number that doesn't correspond to CMC of any of your destructible lands
Winnow - while the condition is interesting, ultimately Winnow can't target lands