diff --git a/core/src/main/java/com/volmit/iris/core/commands/CommandStudio.java b/core/src/main/java/com/volmit/iris/core/commands/CommandStudio.java
index a81e473e6..6ebb7bac1 100644
--- a/core/src/main/java/com/volmit/iris/core/commands/CommandStudio.java
+++ b/core/src/main/java/com/volmit/iris/core/commands/CommandStudio.java
@@ -370,7 +370,7 @@ public class CommandStudio implements DecreeExecutor {
                     int d = radius * 2;
                     KMap<String, AtomicInteger> data = new KMap<>();
                     engine.getDimension().getRegions().forEach(key -> data.put(key, new AtomicInteger(0)));
-                    var multiBurst = new MultiBurst("Region Sampler", Thread.MIN_PRIORITY);
+                    var multiBurst = new MultiBurst("Region Sampler");
                     var executor = multiBurst.burst(radius * radius);
                     sender.sendMessage(C.GRAY + "Generating data...");
                     var loc = player.getLocation();
diff --git a/core/src/main/java/com/volmit/iris/engine/IrisComplex.java b/core/src/main/java/com/volmit/iris/engine/IrisComplex.java
index 1ce21d29d..9435dc822 100644
--- a/core/src/main/java/com/volmit/iris/engine/IrisComplex.java
+++ b/core/src/main/java/com/volmit/iris/engine/IrisComplex.java
@@ -116,6 +116,7 @@ public class IrisComplex implements DataProvider {
                             .getAllBiomes(this)
                             .forEach(this::registerGenerators));
         }
+        boolean legacy = engine.getDimension().isLegacyRarity();
         overlayStream = ProceduralStream.ofDouble((x, z) -> 0.0D).waste("Overlay Stream");
         engine.getDimension().getOverlayNoise().forEach(i -> overlayStream = overlayStream.add((x, z) -> i.get(rng, getData(), x, z)));
         rockStream = engine.getDimension().getRockPalette().getLayerGenerator(rng.nextParallelRNG(45), data).stream()
@@ -129,7 +130,7 @@ public class IrisComplex implements DataProvider {
                 ProceduralStream.of((x, z) -> focusRegion,
                         Interpolated.of(a -> 0D, a -> focusRegion))
                 : regionStyleStream
-                .selectRarity(data.getRegionLoader().loadAll(engine.getDimension().getRegions()))
+                .selectRarity(data.getRegionLoader().loadAll(engine.getDimension().getRegions()), legacy)
                 .cache2D("regionStream", engine, cacheSize).waste("Region Stream");
         regionIDStream = regionIdentityStream.convertCached((i) -> new UUID(Double.doubleToLongBits(i),
                 String.valueOf(i * 38445).hashCode() * 3245556666L)).waste("Region ID Stream");
@@ -138,7 +139,7 @@ public class IrisComplex implements DataProvider {
                         -> engine.getDimension().getCaveBiomeStyle().create(rng.nextParallelRNG(InferredType.CAVE.ordinal()), getData()).stream()
                         .zoom(engine.getDimension().getBiomeZoom())
                         .zoom(r.getCaveBiomeZoom())
-                        .selectRarity(data.getBiomeLoader().loadAll(r.getCaveBiomes()))
+                        .selectRarity(data.getBiomeLoader().loadAll(r.getCaveBiomes()), legacy)
                         .onNull(emptyBiome)
                 ).convertAware2D(ProceduralStream::get).cache2D("caveBiomeStream", engine, cacheSize).waste("Cave Biome Stream");
         inferredStreams.put(InferredType.CAVE, caveBiomeStream);
@@ -148,7 +149,7 @@ public class IrisComplex implements DataProvider {
                         .zoom(engine.getDimension().getBiomeZoom())
                         .zoom(engine.getDimension().getLandZoom())
                         .zoom(r.getLandBiomeZoom())
-                        .selectRarity(data.getBiomeLoader().loadAll(r.getLandBiomes(), (t) -> t.setInferredType(InferredType.LAND)))
+                        .selectRarity(data.getBiomeLoader().loadAll(r.getLandBiomes(), (t) -> t.setInferredType(InferredType.LAND)), legacy)
                 ).convertAware2D(ProceduralStream::get)
                 .cache2D("landBiomeStream", engine, cacheSize).waste("Land Biome Stream");
         inferredStreams.put(InferredType.LAND, landBiomeStream);
@@ -158,7 +159,7 @@ public class IrisComplex implements DataProvider {
                         .zoom(engine.getDimension().getBiomeZoom())
                         .zoom(engine.getDimension().getSeaZoom())
                         .zoom(r.getSeaBiomeZoom())
-                        .selectRarity(data.getBiomeLoader().loadAll(r.getSeaBiomes(), (t) -> t.setInferredType(InferredType.SEA)))
+                        .selectRarity(data.getBiomeLoader().loadAll(r.getSeaBiomes(), (t) -> t.setInferredType(InferredType.SEA)), legacy)
                 ).convertAware2D(ProceduralStream::get)
                 .cache2D("seaBiomeStream", engine, cacheSize).waste("Sea Biome Stream");
         inferredStreams.put(InferredType.SEA, seaBiomeStream);
@@ -167,7 +168,7 @@ public class IrisComplex implements DataProvider {
                         -> engine.getDimension().getShoreBiomeStyle().create(rng.nextParallelRNG(InferredType.SHORE.ordinal()), getData()).stream()
                         .zoom(engine.getDimension().getBiomeZoom())
                         .zoom(r.getShoreBiomeZoom())
-                        .selectRarity(data.getBiomeLoader().loadAll(r.getShoreBiomes(), (t) -> t.setInferredType(InferredType.SHORE)))
+                        .selectRarity(data.getBiomeLoader().loadAll(r.getShoreBiomes(), (t) -> t.setInferredType(InferredType.SHORE)), legacy)
                 ).convertAware2D(ProceduralStream::get).cache2D("shoreBiomeStream", engine, cacheSize).waste("Shore Biome Stream");
         inferredStreams.put(InferredType.SHORE, shoreBiomeStream);
         bridgeStream = focusBiome != null ? ProceduralStream.of((x, z) -> focusBiome.getInferredType(),
diff --git a/core/src/main/java/com/volmit/iris/engine/object/IRare.java b/core/src/main/java/com/volmit/iris/engine/object/IRare.java
index f010046d4..f78931830 100644
--- a/core/src/main/java/com/volmit/iris/engine/object/IRare.java
+++ b/core/src/main/java/com/volmit/iris/engine/object/IRare.java
@@ -25,9 +25,9 @@ import com.volmit.iris.util.stream.interpolation.Interpolated;
 import java.util.List;
 
 public interface IRare {
-    static <T extends IRare> ProceduralStream<T> stream(ProceduralStream<Double> noise, List<T> possibilities) {
-        return ProceduralStream.of((x, z) -> pick(possibilities, noise.get(x, z)),
-                (x, y, z) -> pick(possibilities, noise.get(x, y, z)),
+    static <T extends IRare> ProceduralStream<T> stream(ProceduralStream<Double> noise, List<T> possibilities, boolean legacyRarity) {
+        return ProceduralStream.of(legacyRarity ? (x, z) -> pickLegacy(possibilities, noise.get(x, z)) : (x, z) -> pick(possibilities, noise.get(x, z)),
+                legacyRarity ? (x, y, z) -> pickLegacy(possibilities, noise.get(x, y, z)) : (x, y, z) -> pick(possibilities, noise.get(x, y, z)),
                 new Interpolated<T>() {
                     @Override
                     public double toDouble(T t) {
diff --git a/core/src/main/java/com/volmit/iris/engine/object/IrisDimension.java b/core/src/main/java/com/volmit/iris/engine/object/IrisDimension.java
index 704d0b014..2d7917a6d 100644
--- a/core/src/main/java/com/volmit/iris/engine/object/IrisDimension.java
+++ b/core/src/main/java/com/volmit/iris/engine/object/IrisDimension.java
@@ -257,6 +257,8 @@ public class IrisDimension extends IrisRegistrant {
     @RegistryListResource(IrisScript.class)
     @ArrayType(type = String.class, min = 1)
     private KList<String> dataScripts = new KList<>();
+    @Desc("Use legacy rarity instead of modern one\nWARNING: Changing this may break expressions and image maps")
+    private boolean legacyRarity = true;
 
     public int getMaxHeight() {
         return (int) getDimensionHeight().getMax();
diff --git a/core/src/main/java/com/volmit/iris/util/stream/ProceduralStream.java b/core/src/main/java/com/volmit/iris/util/stream/ProceduralStream.java
index e860f299a..539a0f224 100644
--- a/core/src/main/java/com/volmit/iris/util/stream/ProceduralStream.java
+++ b/core/src/main/java/com/volmit/iris/util/stream/ProceduralStream.java
@@ -336,6 +336,7 @@ public interface ProceduralStream<T> extends ProceduralLayer, Interpolated<T> {
     }
 
     @SuppressWarnings("unchecked")
+    @Deprecated(forRemoval = true)
     default <V> ProceduralStream<V> selectRarity(V... types) {
         KList<V> rarityTypes = new KList<>();
         int totalRarity = 0;
@@ -350,16 +351,16 @@ public interface ProceduralStream<T> extends ProceduralLayer, Interpolated<T> {
         return new SelectionStream<V>(this, rarityTypes);
     }
 
-    default <V extends IRare> ProceduralStream<V> selectRarity(List<V> types) {
-        return IRare.stream(this.forceDouble(), types);
+    default <V extends IRare> ProceduralStream<V> selectRarity(List<V> types, boolean legacy) {
+        return IRare.stream(this.forceDouble(), types, legacy);
     }
 
-    default <V> ProceduralStream<IRare> selectRarity(List<V> types, Function<V, IRare> loader) {
+    default <V> ProceduralStream<IRare> selectRarity(List<V> types, Function<V, IRare> loader, boolean legacy) {
         List<IRare> r = new ArrayList<>();
         for (V f : types) {
             r.add(loader.apply(f));
         }
-        return selectRarity(r);
+        return selectRarity(r, legacy);
     }
 
     default <V> int countPossibilities(List<V> types, Function<V, IRare> loader) {