diff --git a/README.md b/README.md
index 442d72ff50..bda12fa88b 100644
--- a/README.md
+++ b/README.md
@@ -30,10 +30,14 @@ Please have a look at the [naming conventions](/CONVENTIONS.md) before submittin
 Yarn uses Gradle to provide a number of utility tasks for working with the mappings.
 
 ### `yarn`
-[`setupYarn`](#setupYarn) and download and launch the latest version of [Enigma](https://github.com/FabricMC/Enigma) automatically configured to use the merged jar and the mappings.
+Setup and download and launch the latest version of [Enigma](https://github.com/FabricMC/Enigma) automatically configured to use the merged jar and the mappings.
 
 Compared to launching Enigma externally, the gradle task adds a name guesser plugin that automatically map enums and a few constant field names.
 
+### `yarnUnpicked`
+Same as above, but unpicks the constants and launches engima with them. Can be a little bit slower to get going.
+
+
 ### `build`
 Build a GZip'd archive containing a tiny mapping between official (obfuscated), [intermediary](https://github.com/FabricMC/intermediary), and yarn names ("named") and packages enigma mappings into a zip archive..
 
@@ -48,6 +52,3 @@ Downloads the client and server Minecraft jars for the current Minecraft version
 
 ### `mergeJars`
 Merges the client and server jars into one merged jar, located at `VERSION-merged.jar` in the mappings directory where `VERSION` is the current Minecraft version.
-
-### `setupYarn`
-[`download`](#download) and [`mergeJars`](#mergeJars)
diff --git a/build.gradle b/build.gradle
index 5c6537e66c..ed15602628 100644
--- a/build.gradle
+++ b/build.gradle
@@ -5,6 +5,7 @@ buildscript {
 			url 'https://maven.fabricmc.net'
 		}
 		mavenCentral()
+		mavenLocal()
 	}
 	dependencies {
 		classpath "cuchaz:enigma-cli:${project.enigma_version}"
@@ -12,6 +13,9 @@ buildscript {
 		classpath "commons-io:commons-io:2.6"
 		classpath 'de.undercouch:gradle-download-task:4.0.4'
 		classpath 'net.fabricmc:tiny-remapper:0.3.1.72'
+		classpath 'net.fabricmc:mappingpoet:0.1.0+build.2'
+		classpath 'net.fabricmc.unpick:unpick:2.0.1'
+		classpath 'net.fabricmc.unpick:unpick-format-utils:2.0.1'
 	}
 }
 
@@ -29,6 +33,7 @@ def ENV = System.getenv()
 def build_number = ENV.BUILD_NUMBER ?: "local"
 
 def yarnVersion = "${minecraft_version}+build.$build_number"
+version = yarnVersion
 
 repositories {
 	mavenCentral()
@@ -40,6 +45,7 @@ repositories {
 		name "Mojang"
 		url 'https://libraries.minecraft.net/'
 	}
+	mavenLocal()
 }
 
 configurations {
@@ -58,8 +64,12 @@ configurations {
 		extendsFrom mappingPoetJar
 		transitive = true
 	}
+	unpick
 }
 
+def unpickMetaFile = file("unpick-definitions/unpick.json")
+def unpickMeta = new groovy.json.JsonSlurper().parseText(unpickMetaFile.text)
+
 dependencies {
 	enigmaRuntime "cuchaz:enigma-swing:${project.enigma_version}"
 	enigmaRuntime "net.fabricmc:stitch:${project.stitch_version}"
@@ -67,6 +77,7 @@ dependencies {
 	javadocClasspath "org.jetbrains:annotations:${project.jetbrains_annotations_version}"
 	decompileClasspath "org.benf:cfr:0.150"
 	mappingPoetJar 'net.fabricmc:mappingpoet:0.2.6'
+	unpick "${unpickMeta.unpickGroup}:unpick-cli:${unpickMeta.unpickVersion}"
 }
 
 def setupGroup = "jar setup"
@@ -78,6 +89,7 @@ def cacheFilesMinecraft = file(".gradle/minecraft")
 def tempDir = file(".gradle/temp")
 def mergedFile = file("${minecraft_version}-merged.jar")
 def intermediaryJar = file("${minecraft_version}-intermediary.jar")
+def unpickedJar = file("${minecraft_version}-intermediary-unpicked.jar")
 def namedJar = file("${minecraft_version}-named.jar")
 def versionFile = new File(cacheFilesMinecraft, "${minecraft_version}.json")
 def clientJar = new File(cacheFilesMinecraft, "${minecraft_version}-client.jar")
@@ -361,11 +373,28 @@ task mapIntermediaryJar(dependsOn: [downloadMcLibs, downloadIntermediary, mergeJ
 	}
 }
 
-task setupYarn(dependsOn: mapIntermediaryJar) {
+task yarnUnpicked(dependsOn: "unpickIntermediaryJar") {
 	group = yarnGroup
+	doLast {
+		ant.setLifecycleLogLevel "WARN"
+		ant.java(
+				classname: 'cuchaz.enigma.gui.Main',
+				classpath: configurations.enigmaRuntime.asPath,
+				fork: true,
+				spawn: true
+		) {
+			jvmarg(value: "-Xmx2048m")
+			arg(value: '-jar')
+			arg(value: unpickedJar.getAbsolutePath())
+			arg(value: '-mappings')
+			arg(value: mappingsDir.getAbsolutePath())
+			arg(value: '-profile')
+			arg(value: 'enigma_profile.json')
+		}
+	}
 }
 
-task yarn(dependsOn: setupYarn) {
+task yarn(dependsOn: mapIntermediaryJar) {
 	group = yarnGroup
 	doLast {
 		ant.setLifecycleLogLevel "WARN"
@@ -574,7 +603,7 @@ task buildTinyWithEnum(dependsOn: "mergeTiny", type: FileOutput) {
 	}
 }
 
-task mapNamedJar(dependsOn: ["mergeV2", mapIntermediaryJar]) {
+task mapNamedJar(dependsOn: ["mergeV2", "unpickIntermediaryJar"]) {
 	group = mapJarGroup
 	inputs.files downloadMcLibs.outputs.files.files
 	outputs.file(namedJar)
@@ -591,7 +620,7 @@ task mapNamedJar(dependsOn: ["mergeV2", mapIntermediaryJar]) {
 	doLast {
 		logger.lifecycle(":mapping minecraft to named")
 
-		mapJar(namedJar, intermediaryJar, mergeV2.output, libraries, "intermediary", "named") {
+		mapJar(namedJar, unpickedJar, mergeV2.output, libraries, "intermediary", "named") {
 			it.withMappings { out ->
 				jsrToJetbrains.each { e ->
 					out.acceptClass e.key, e.value
@@ -601,6 +630,133 @@ task mapNamedJar(dependsOn: ["mergeV2", mapIntermediaryJar]) {
 	}
 }
 
+import daomephsta.unpick.constantmappers.datadriven.parser.v2.UnpickV2Reader
+import daomephsta.unpick.constantmappers.datadriven.parser.v2.UnpickV2Writer
+import daomephsta.unpick.constantmappers.datadriven.parser.v2.UnpickV2Remapper
+import daomephsta.unpick.constantmappers.datadriven.parser.MethodKey
+import net.fabricmc.mapping.tree.TinyMappingFactory
+
+// Merge all of the unpick definitions into a single file to be shipped
+task combineUnpickDefinitions(type : FileOutput) {
+	output = new File(tempDir, "definitions.unpick")
+	outputs.upToDateWhen { false }
+	group "unpick"
+
+	doFirst {
+		output.delete()
+	}
+
+	doLast {
+		def writer = new UnpickV2Writer()
+
+		file("unpick-definitions").eachFile {
+			if (!it.name.endsWith(".unpick")) {
+				return
+			}
+
+			it.withInputStream {
+				new UnpickV2Reader(it).withCloseable {
+					it.accept(writer)
+				}
+			}
+		}
+
+		output.text = writer.output
+	}
+}
+
+task remapUnpickDefinitionsIntermediary(type : FileOutputInput, dependsOn: [combineUnpickDefinitions, buildYarnTiny]) {
+	output = new File(tempDir, "intermediary-definitions.unpick")
+	input = combineUnpickDefinitions.output
+	File mappingsInput = buildYarnTiny.v2Output
+
+	outputs.upToDateWhen { false }
+	group "unpick"
+
+	doFirst {
+		output.delete()
+	}
+
+	doLast {
+		def classMappings = [:]
+		def methodMappings = [:]
+
+		mappingsInput.withReader {reader ->
+			def tinyTree = TinyMappingFactory.loadWithDetection(reader)
+
+			tinyTree.classes.each { classDef ->
+				classMappings.put(
+					classDef.getName("named"),
+					classDef.getName("intermediary")
+				)
+
+				classDef.methods.each { methodDef ->
+					methodMappings.put(
+						new MethodKey(
+							classDef.getName("named"),
+							methodDef.getName("named"),
+							methodDef.getDescriptor("named")
+						),
+						methodDef.getName("intermediary")
+					)
+				}
+			}
+		}
+
+		input.withInputStream {
+			new UnpickV2Reader(it).withCloseable {reader ->
+				def writer = new UnpickV2Writer()
+				reader.accept(new UnpickV2Remapper(classMappings, methodMappings, writer))
+				output.text = writer.output
+			}
+		}
+	}
+}
+
+task unpickIntermediaryJar(type: JavaExec, dependsOn: [mapIntermediaryJar, "constantsJar", remapUnpickDefinitionsIntermediary]) {
+	outputs.upToDateWhen { false }
+	group "unpick"
+
+	main "daomephsta.unpick.cli.Main"
+	classpath configurations.unpick
+
+	doFirst {
+		args intermediaryJar.absolutePath, unpickedJar.absolutePath, remapUnpickDefinitionsIntermediary.output.absolutePath, constantsJar.archiveFile.get().asFile.absolutePath, intermediaryJar.absolutePath
+
+		configurations.decompileClasspath.files.each {
+			args it.absolutePath
+		}
+	}
+}
+
+// Setup the build for the unpicked constants
+
+sourceCompatibility = JavaVersion.VERSION_1_8
+targetCompatibility = JavaVersion.VERSION_1_8
+
+tasks.withType(JavaCompile).configureEach {
+	it.options.encoding = "UTF-8"
+	if (JavaVersion.current().isJava9Compatible()) {
+		it.options.release = 8
+	}
+}
+
+sourceSets {
+	constants
+}
+
+task constantsJar(type: Jar) {
+	from sourceSets.constants.output
+	archiveClassifier = "constants"
+}
+
+task sourcesJar(type: Jar, dependsOn: classes) {
+	archiveClassifier = "sources"
+	from sourceSets.constants.allSource
+}
+
+build.dependsOn constantsJar
+
 task insertAutoGeneratedEnumMappings(dependsOn : [buildYarnTiny,mapIntermediaryJar], type : FileOutput){
 	group = buildMappingGroup
 	def noEnumV2 = buildYarnTiny.v2Output
@@ -652,7 +808,7 @@ task mergeV2(dependsOn: ["v2UnmergedYarnJar", "invertIntermediaryv2"], type: Fil
 	}
 }
 
-task v2UnmergedYarnJar(dependsOn: insertAutoGeneratedEnumMappings, type: Jar) {
+task v2UnmergedYarnJar(dependsOn: [insertAutoGeneratedEnumMappings, combineUnpickDefinitions], type: Jar) {
 	def mappings = insertAutoGeneratedEnumMappings.output
 	group = "mapping build"
 	outputs.upToDateWhen { false }
@@ -661,6 +817,12 @@ task v2UnmergedYarnJar(dependsOn: insertAutoGeneratedEnumMappings, type: Jar) {
 	from(file(mappings)) {
 		rename mappings.name, "mappings/mappings.tiny"
 	}
+	from(combineUnpickDefinitions.output) {
+		rename combineUnpickDefinitions.output.name, "extras/definitions.unpick"
+	}
+	from (file(unpickMetaFile)) {
+		rename unpickMetaFile.name, "extras/unpick.json"
+	}
 	destinationDirectory.set(file("build/libs"))
 }
 
@@ -673,6 +835,12 @@ task v2MergedYarnJar(dependsOn: ["mergeV2"], type: Jar) {
 	from(file(mappings)) {
 		rename mappings.name, "mappings/mappings.tiny"
 	}
+	from(combineUnpickDefinitions.output) {
+		rename combineUnpickDefinitions.output.name, "extras/definitions.unpick"
+	}
+	from (file(unpickMetaFile)) {
+		rename unpickMetaFile.name, "extras/unpick.json"
+	}
 	destinationDirectory.set(file("build/libs"))
 }
 
@@ -697,7 +865,7 @@ task genFakeSource(type: JavaExec, dependsOn: ["mergeV2", "mapNamedJar"]) {
 	}
 }
 
-task decompileCFR(type: JavaExec, dependsOn: "mapNamedJar") {
+task decompileCFR(type: JavaExec, dependsOn: [mapNamedJar]) {
 	classpath = configurations.decompileClasspath
 	main = "org.benf.cfr.reader.Main"
 
@@ -811,6 +979,10 @@ publishing {
 			artifact(v2MergedYarnJar) {
 				classifier "mergedv2"
 			}
+			artifact(constantsJar) {
+				classifier "constants"
+			}
+			artifact sourcesJar
 			artifact javadocJar
 		}
 
@@ -864,6 +1036,14 @@ class FileOutput extends DefaultTask {
 	File output
 }
 
+class FileOutputInput extends DefaultTask {
+	@InputFile
+	File input
+
+	@OutputFile
+	File output
+}
+
 class WithV2FileOutput extends DefaultTask {
 	@OutputFile
 	File v1Output
diff --git a/src/constants/java/net/fabricmc/yarn/constants/SetBlockStateFlags.java b/src/constants/java/net/fabricmc/yarn/constants/SetBlockStateFlags.java
new file mode 100644
index 0000000000..852af85789
--- /dev/null
+++ b/src/constants/java/net/fabricmc/yarn/constants/SetBlockStateFlags.java
@@ -0,0 +1,46 @@
+package net.fabricmc.yarn.constants;
+
+public final class SetBlockStateFlags {
+	/**
+	 * Propagates a change event to surrounding blocks.
+	 */
+	public static final int PROPAGATE_CHANGE = 1;
+
+	/**
+	 * Notifies listeners and clients who need to react when the block changes.
+	 */
+	public static final int NOTIFY_LISTENERS = 2;
+
+	/**
+	 * Used in conjunction with {@link NOTIFY_LISTENERS} to suppress the render pass on clients.
+	 */
+	public static final int NO_REDRAW = 4;
+
+	/**
+	 * Forces a synchronous redraw on clients.
+	 */
+	public static final int REDRAW_ON_MAIN_THREAD = 8;
+
+	/**
+	 * Bypass virtual block state changes and forces the passed state to be stored as-is.
+	 */
+	public static final int FORCE_STATE = 16;
+
+	/**
+	 * Prevents the previous block (container) from dropping items when destroyed.
+	 */
+	public static final int SKIP_DROPS = 32;
+
+	/**
+	 * Signals that the current block is being moved to a different location, usually because of a piston.
+	 */
+	public static final int MOVED = 64;
+
+	/**
+	 * Signals that lighting updates should be skipped.
+	 */
+	public static final int SKIP_LIGHTING_UPDATES = 128;
+
+	private SetBlockStateFlags() {
+	}
+}
diff --git a/unpick-definitions/set_block_state_flags.unpick b/unpick-definitions/set_block_state_flags.unpick
new file mode 100644
index 0000000000..faaf9e745e
--- /dev/null
+++ b/unpick-definitions/set_block_state_flags.unpick
@@ -0,0 +1,13 @@
+v2
+
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags PROPAGATE_CHANGE
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags NOTIFY_LISTENERS
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags NO_REDRAW
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags REDRAW_ON_MAIN_THREAD
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags FORCE_STATE
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags SKIP_DROPS
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags MOVED
+flag set_block_state_flags net/fabricmc/yarn/constants/SetBlockStateFlags SKIP_LIGHTING_UPDATES
+
+target_method net/minecraft/world/ModifiableWorld setBlockState (Lnet/minecraft/util/math/BlockPos;Lnet/minecraft/block/BlockState;I)Z
+	param 2 set_block_state_flags
\ No newline at end of file
diff --git a/unpick-definitions/unpick.json b/unpick-definitions/unpick.json
new file mode 100644
index 0000000000..8869787b56
--- /dev/null
+++ b/unpick-definitions/unpick.json
@@ -0,0 +1,5 @@
+{
+  "version": 1,
+  "unpickGroup": "net.fabricmc.unpick",
+  "unpickVersion": "2.0.1"
+}
\ No newline at end of file