Need:
Rockfall Vale - Fixing that should ETB untapped most of the time

Consider:
Rob the Archives - Can get me 4 cards for 2 mana!
* Gleeful Demolition - Cheap artifact removal, or turn a treasure into 3 (or 6) goblins
Dockside Extortionist - Goblin ramp
Awaken the Woods - Make a buuunch of both mana and green creatures for future copying
* Valakut Awakening - Card draw that can be a land in an emergency, but currently used in Hofri
Jaya, Fiery Negotiator - Make red monks, card "draw", removal are all relevant abilities, but the real reason to consider this is the ult which lets me copy a spell twice
Tibalt's Trickery - Protection
Reckless Impulse - "Draw" a bunch of cards
Crop Rotation - Ramps with a copy spell, or can get a utility land, e.g. Valakut before getting a large number of mountains
Twinferno - Cheap copier, but needs to be played up front
* Pyroblast/REB - Counter a counter or destroy something scary for cheap
* Guttersnipe - Chip damage that can conspire and is a goblin, but will probably eat removal
* Krosan Grip - Uncounterable and can be conspired
* Bonus Round - Copy all the things in one round. Conspiring this will copy everything twice
* Repeated Reverberation - Copy something twice, or 4x if copying this
Verdant Command - Tokens, graveyard hate or counter a planeswalker ability
* Underworld Breach - Can let me win late-game if I don't have all I need in hand
Harmonic Prodigy - Double conspire, and we have a few other interesting targets: EWit, Dualcaster, Young Pyro and Storm-Kiln
Brass's Bounty - Expensive to cast initially, but does allow me to store the mana for later. It will probably make me a threat, but it might give me enough mana to go off
Arbor Elf - Dork that can potentially tap to get me red mana
Scute Swarm - lots of tokens!
Birgi, God of Storytelling - Basically a discount on spells
Moraug, Fury of Akoum - More combats, but my creatures are probably too small for this to be relevant, especially considering the amount of consistent landfall
Deflecting Swat - Protection for Wort
Nature's Claim
Roiling Regrowth - Saccing is not an additional cost so can't be skipped, but this could fetch a decent amount of lands
Seething Song - Big ritual
Pest Infestation - X-cost artifact/enchantment removal with token generation
Saproling Migration - Green Krenko's Command that can be kicked for twice the amount of tokens
Past in Flames - Try to go off with the stuff in my graveyard, but might be tough without rituals
Wild Guess - Tormented Voice for RR, so it's a bit hard to cast early
Veil of Summer - Counter protection or a cantrip in a pinch
Brightstone Ritual - Goblin ritual
Sprout Swarm - Green tokens
Arachnogenesis - Protect from a big swing or get a bunch of tokens for later when attacked
Price of Progress - A cheap spell that could finish off a few players, but not very flexible or consistent
Return to Nature - Flexible removal
Vandalblast - Artifact wipe
Backdraft Hellkite - Dragon giving out flashback
Beacon of Creation - Green tokens, but doesn't do much if I don't already have lots of forests
Haze of Rage - In magical christmas land this is a cheap wincon, but it's probably rarely going to get more than 2, maybe 3 copies, and no added toughness means my goblins will likely die anyway, so the buyback is also not very important
Descent of the Dragons - Upgrade my goblins with the option of downgrading scary creatures of my opponents, but the dragons won't have haste so not sure how useful this is
Burn Bright/Trumpet Blast - Cheap ways to pump a bunch of goblins to maybe sneak in a kill, but probably not going to do much usually
Overcome - An extra overrun effect, but slightly worse
In the Web of War - Make my small tokens a little bit scarier and much faster
Protection for Wort (shoes, cloaks etc)

Elfhame Druid, Fyndhorn Elves, Fyndhorn Elder, Scorned Villager - Mana dorks that can tap to conspire green spells
Arasta of the Endless Web - Get tokens whenever opponents cast spells, but they are mono green and how many will I even get?
Charmbreaker Devils - Random Regrowth every turn on a dude that can be scary
Skirk Prospector - Sac my dudes for mana in response to a Rift or to cash in for a game-ending Banefire?
Krark, the Thumbless - Goblin with double or nothing: if I have copied a spell, I either get another copy or get to recast the original later. I can't choose, though
Krenko, Tin-Street Kingpin - Goblin creator, but needs to be able to attack
Tendershoot Dryad - Lots of tokens, but green only
Grumgully - Multicolored goblin that makes my tokens a bit bigger
Omnath, Locus of Rage - Big scary token creator
* Goblin Matron - Tutor up Krenko, Pashalik/Siege-Gang, Vexing Shusher depending on what I need
Ant Queen - Token factory/mana sink
Grenzo, Havoc Raiser - Throw a bunch of gobbos to open up for an alpha strike next turn
Torbran - Everything gets a bit scarier
Wild Cantor - Cheap RG dude that can be sacced to recoup the mana
Mina and Denn - RG dude with extra land drops
Llanowar Mentor - Turn useless cards into Llanowar Elves
Thermopod - A bigger Skirk Prospector that can also sac other things
Tana, the Bloodsower - A RG dude that makes more dudes, but needs to be able to connect

Dryad Arbor - Land that can conspire
* Reliquary Tower - I can draw quite a lot of cards
Highland Forest
Castle Embereth - A land that can make my goblins hit a little bit harder
Forgotten Cave - Cycle when I have excessive red mana

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Consider (don't have):
* $ Early Harvest - A ritual that can semi-whiff if I have the wrong lands, and is hard to copy because my creatures are mostly red
Titania's Command - Graveyard hate and life gain, green tokens, counters for a potential combat finisher, and possibly ramp if necessary. All modes are good, but it does cost 6 mana and is mono-green, so harder to copy
Storm King's Thunder - Playing this for 5 or 6 mana and copying it will let me copy the next spell 4-6 times
$ Ezuri's Predation - Mostly a token generator that also clears small creatures
Inspired Tinkering - "Draw" 3 and get 3 treasures
$ Sheltered Thicket - More copies
$$ Dragon Broodmother - Lots of tokens that are both colors, and can even get big. I can get 4 per turn cycle, but it might not be explosive enough to be worth the 6 mana. More of a grindy card, but getting it removed is really bad
Bothersome Quasit - Protection (and removal/damage) through spell slinging
Change of Fortune - Draw a bunch of cards after a Cathartic Reunion
$ Boundless Realms - Double my lands, or quadruple if copied
$ Goblin Offensive - Can make a ton of goblins when I have the mana for it, but until X is at least 6 or 7, the rate is probably not going to be worth it
Chancellor of the Forge - Double my board
$ Kamahl, Heart of Krosa - Make my tokens scary or finish with my lands

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Considered cuts:
Eternal Witness - Might have too many regrowth effects, but this one can conspire
Siege-Gang Commander - Gets me 4 bodies and a way to remove small stuff by flinging my goblins, but it can't be copied and the goblin-flinging is costly
Goblin War Party - I probably don't need the pump part of this, in which case it's a somewhat inefficient goblin creator. The haste could be useful, though
You See a Pair of Goblins
Elves
Impact Tremors - A nice way to get life totals down across the board, but it does make me a target and doesn't do much late
Skyshroud Claim
Regrowth
Empty the Warrens - Bad as the only spell, playable at 2 spells, good at 3. Depends on how often I cast 3 spells in a turn?
Young Pyro

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Cuts:
Zendikar Resurgent - I don't play enough creatures to make use of that end, and I have enough other ways to make explosive amounts of mana that I don't need the threat this generates
Devil's Play - I probably don't need 5 Fireballs + Treacherous Terrain, and this is probably the worst one
Mirari - Copying is the name of the game, but I don't really want to pay 3 each time
Hornet Nest - Without pingers, I probably won't get much value out of this
Nissa's Renewal - Quite expensive for a ramp spell, although it's great if I can copy it, and it's nice to have a source of lifegain. Replaced by Grow from the Ashes
? Fall of the Titans - Cut down amount of fireballs. Can target two targets, and be cast instant speed, but needs another spell to enable
Beetleback Chief - Gives me three goblins, but can't be copied
Goblinslide - Paying a mana for the goblins is actually a little expensive, but they do gain haste
Hornet Queen - 7 mana for 5 dudes is good, but they are only green
Goblin Trashmaster - Can't Skullclamp 2/2s, but getting rid of artifacts at will is nice
Broken Bond - Green spells are harder to copy, but this is great to destroy someone else's early mana advantage and ramp a little myself. Might not have extra lands in hand that often, though
Jaya Ballard - Nice to draw out of a slump, but it's hard to protect and isn't worth much if I can only use it once
Rosheen Meanderer - Pretty slow, and the mana can't be used for most things
? Banefire - Reduced number of fireballs. This is uncounterable, but can only hit one target until copied, so requires a lot of mana to kill someone.
Mizzium Mortars - 6 mana is actually a fair amount, while only doing 4 damage. It's not likely to kill the really important stuff until I have Wort out. Consider putting back in if I'm lacking in control
Temple of the False God - Only have 35 lands, and getting this as one of my few early ones is terrible
Goblin Bombardment - I only really want to sac my dudes in the face of a board wipe, although this also works as removal or a finisher as well
Grand Warlord Radha - I can rarely attack with my small dudes, so this is probably not going to make a lot of mana unless I sacrifice a board, in which case I could probably just have used Skirk Prospector. This is RG, though
Rishkar's Expertise - We don't have a lot of big stuff, and others decks probably needs this more, but drawing 2 then casting a 5-drop is still pretty good, and if I can copy it it's great value
Reiterate - How often do I want to/can I spend 6 mana to copy something?
Grow from the Ashes - Probably the worst ramp spell if I can't copy it, but a pretty good spell to copy. Replaced with more consistent option
Revel of the False God - Very expensive for four tokens. Besides being RG, these tokens will usually not be big enough that the haste and increased power matters over a cheaper token generator
Wildest Dreams - XX is probably too much to be worth it and I'm better off playing a cheaper Regrowth
Subterranean Tremors - Doesn't kill fliers, and copying it doesn't actually copy any of the added benefits
Blighted Woodland - I have a lot of color requirements and a lot of ramp already
Growing Rites - I don't have that many creatures this can hit, but the Cradle is nice
Sunbird's Invocation - Most of my spells will not be so expensive that this is likely to hit a castable target
Overrun - The goblins are not large enough in the first place for this to commonly be enough, although with a wide enough board it could be relevant
Mycoloth - I don't really want to sac my dudes, but if I only sac one it replaces itself immediately and pays me back double next turn
Treacherous Terrain - Mostly only useful as a game ender, and I can't even guarantee it will end the game. Decent backup as a way to get a third land, though
Evolving Wilds - I don't have anything to gain from putting lands in the graveyard, so a straight RG land is better
Wild Ricochet - How often will the redirect PLUS copy be relevant that I shouldn't just be playing a cheaper copier?
Chain Reaction - This will often wipe a full board, but it doesn't deal well with few large creatures, and I'm likely to lose a lot as well. Plus copying it does not equal double damage and can get complicated
Return of the Wildspeaker - Card draw or pump my team, but no trample and requires a big creature to draw efficiently. Instant speed helps the no-trample part.
Destructive Revelry - "Only" destroys an artifact/enchantment, but is easy to copy
? Heroic Intervention - Protect my board, but how much of a board do I even have to protect?
Tranquil Thicket - ETBT and green-only, not sure I need the cycling upside
Rude Awakening - How often am I going to use the lands to creatures mode? Combos with Harvest Season, but that's at 8 mana
Pashalik Mons - Expensive and slow to use, but a nice sweeper deterrant
Zhur-Taa Druid, Radha Heir to Keld - Fragile and mana-inefficient dorks that can conspire both colors, but they can't conspire and tap for mana on the same turn, and I have enough goblin tokens that I don't need the red bodies
Throne of the God-Pharaoh - Helps wither down life totals, but if I'm able to tap enough creatures for this to be relevant, I'm probably doing great already. It's probably going to draw more focus to me than it's going to help
? Twinflame - Infinite combo with Dualcaster Mage (+ any creature), but does basically nothing without the mage since it can only copy my creatures
Raging Ravine - 4 mana to activate is just too much to use this to conspire
Goblin Rally - Gets a bunch of gobbos, but the rate is not great and it's so expensive that I won't be able to cast many more spells that turn
Clan Defiance - I don't really want to use this as removal, in which case I would prefer something that can hit multiple players, like Jaya's Immolating Inferno
Heat Shimmer - Infinite combo with Dualcaster Mage (+ any creature), but can potentially do nothing without the mage
Dualcaster Mage - A copier that leaves behind a conspirator, but if I play this I "have to" play Twinflame/Heat Shimmer as well
Ghost Quarter - Maybe someone else can handle lands? I have heavy color requirements
? Volcanic Vision - Expensive Regrowth with an unreliable board wipe attached to it. If I can copy it, it's probably usually going to be good enough, but I don't have a lot of targets this can get that will reliably wipe a board without being copied
Parallel Lives - Doubles tokens, but it immediately puts a target on me, and does actual nothing if I can't produce tokens in the first place
Howl of the Horde - Requires attacking to get proper value
Migration Path - 4 mana for 2 tapped basics is quite a bit, but being able to cycle if I don't need it (or I need to draw lands to get to 4) is nice
Dragonlair Spider - Expensive, and not guaranteed to make me a lot of dudes, AND they are only green. It is a huge body for blocking fliers, though
Pyromancer's Goggles - Can only copy red spells, and it's a bit expensive as just a ramp option