You can no longer place solid blocks on non-solid cloud blocks

src/main/java/com/minelittlepony/unicopia/block/BlockCloud.java

@@ -15,7 +15,6 @@ import net.minecraft.block.properties.IProperty;
 import net.minecraft.block.properties.PropertyEnum;
 import net.minecraft.block.state.BlockStateContainer;
 import net.minecraft.block.state.IBlockState;
-import net.minecraft.client.Minecraft;
 import net.minecraft.creativetab.CreativeTabs;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.player.EntityPlayer;
@@ -194,11 +193,9 @@ public class BlockCloud extends Block implements ICloudBlock, ITillable {
     @Deprecated
     @Override
     public RayTraceResult collisionRayTrace(IBlockState blockState, World worldIn, BlockPos pos, Vec3d start, Vec3d end) {
-        if (worldIn.isRemote) {
+        if (handleRayTraceSpecialCases(worldIn, pos, blockState)) {
-            if (!getCanInteract(blockState, Minecraft.getMinecraft().player)) {
             return null;
         }
-        }
         return super.collisionRayTrace(blockState, worldIn, pos, start, end);
     }
 

src/main/java/com/minelittlepony/unicopia/block/BlockCloudAnvil.java

@@ -22,6 +22,8 @@ import net.minecraft.util.EnumHand;
 import net.minecraft.util.NonNullList;
 import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.RayTraceResult;
+import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.IBlockAccess;
 import net.minecraft.world.World;
 
@@ -146,6 +148,15 @@ public class BlockCloudAnvil extends BlockAnvil implements ICloudBlock {
         }
     }
 
+    @Deprecated
+    @Override
+    public RayTraceResult collisionRayTrace(IBlockState blockState, World worldIn, BlockPos pos, Vec3d start, Vec3d end) {
+        if (handleRayTraceSpecialCases(worldIn, pos, blockState)) {
+            return null;
+        }
+        return super.collisionRayTrace(blockState, worldIn, pos, start, end);
+    }
+
     @Deprecated
     @Override
     public float getPlayerRelativeBlockHardness(IBlockState state, EntityPlayer player, World worldIn, BlockPos pos) {

src/main/java/com/minelittlepony/unicopia/block/BlockCloudFarm.java

@@ -9,7 +9,6 @@ import com.minelittlepony.unicopia.UBlocks;
 
 import net.minecraft.block.SoundType;
 import net.minecraft.block.state.IBlockState;
-import net.minecraft.client.Minecraft;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.player.EntityPlayer;
 import net.minecraft.util.BlockRenderLayer;
@@ -105,11 +104,9 @@ public class BlockCloudFarm extends UFarmland implements ICloudBlock {
     @Deprecated
     @Override
     public RayTraceResult collisionRayTrace(IBlockState blockState, World worldIn, BlockPos pos, Vec3d start, Vec3d end) {
-        if (worldIn.isRemote) {
+        if (handleRayTraceSpecialCases(worldIn, pos, blockState)) {
-            if (!getCanInteract(blockState, Minecraft.getMinecraft().player)) {
             return null;
         }
-        }
         return super.collisionRayTrace(blockState, worldIn, pos, start, end);
     }
 

src/main/java/com/minelittlepony/unicopia/block/BlockCloudSlab.java

@@ -16,7 +16,6 @@ import net.minecraft.block.properties.IProperty;
 import net.minecraft.block.properties.PropertyEnum;
 import net.minecraft.block.state.BlockStateContainer;
 import net.minecraft.block.state.IBlockState;
-import net.minecraft.client.Minecraft;
 import net.minecraft.creativetab.CreativeTabs;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.player.EntityPlayer;
@@ -113,11 +112,9 @@ public class BlockCloudSlab extends BlockSlab implements ICloudBlock {
     @Deprecated
     @Override
     public RayTraceResult collisionRayTrace(IBlockState blockState, World worldIn, BlockPos pos, Vec3d start, Vec3d end) {
-        if (worldIn.isRemote) {
+        if (handleRayTraceSpecialCases(worldIn, pos, blockState)) {
-            if (!getCanInteract(blockState, Minecraft.getMinecraft().player)) {
             return null;
         }
-        }
         return super.collisionRayTrace(blockState, worldIn, pos, start, end);
     }
 

src/main/java/com/minelittlepony/unicopia/block/BlockCloudStairs.java

@@ -12,7 +12,6 @@ import net.minecraft.block.BlockSlab.EnumBlockHalf;
 import net.minecraft.block.BlockStairs;
 import net.minecraft.block.state.BlockFaceShape;
 import net.minecraft.block.state.IBlockState;
-import net.minecraft.client.Minecraft;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.player.EntityPlayer;
 import net.minecraft.util.EnumFacing;
@@ -108,11 +107,9 @@ public class BlockCloudStairs extends BlockStairs implements ICloudBlock {
     @Deprecated
     @Override
     public RayTraceResult collisionRayTrace(IBlockState blockState, World worldIn, BlockPos pos, Vec3d start, Vec3d end) {
-        if (worldIn.isRemote) {
+        if (handleRayTraceSpecialCases(worldIn, pos, blockState)) {
-            if (!getCanInteract(blockState, Minecraft.getMinecraft().player)) {
             return null;
         }
-        }
         return super.collisionRayTrace(blockState, worldIn, pos, start, end);
     }
 

src/main/java/com/minelittlepony/unicopia/block/ICloudBlock.java

@@ -4,15 +4,55 @@ import com.minelittlepony.unicopia.CloudType;
 
 import net.minecraft.block.Block;
 import net.minecraft.block.BlockFalling;
+import net.minecraft.block.BlockTorch;
 import net.minecraft.block.state.IBlockState;
+import net.minecraft.client.Minecraft;
 import net.minecraft.entity.Entity;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.init.Blocks;
+import net.minecraft.item.ItemBlock;
+import net.minecraft.item.ItemStack;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.IBlockAccess;
+import net.minecraft.world.World;
 
 public interface ICloudBlock {
 
     CloudType getCloudMaterialType(IBlockState blockState);
 
+    default boolean handleRayTraceSpecialCases(World world, BlockPos pos, IBlockState state) {
+        if (world.isRemote) {
+            EntityPlayer player = Minecraft.getMinecraft().player;
+
+            if (!getCanInteract(state, player)) {
+                return true;
+            }
+
+            ItemStack main = player.getHeldItemMainhand();
+            if (main.isEmpty()) {
+                main = player.getHeldItemOffhand();
+            }
+
+            if (!main.isEmpty() && main.getItem() instanceof ItemBlock) {
+                Block block = ((ItemBlock)main.getItem()).getBlock();
+
+                if (block == null) {
+                    return false;
+                }
+
+                if (block instanceof BlockTorch && getCloudMaterialType(state) != CloudType.NORMAL) {
+                    return false;
+                }
+
+                if (block != Blocks.AIR && !(block instanceof ICloudBlock)) {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
     default boolean getCanInteract(IBlockState state, Entity e) {
         return getCloudMaterialType(state).canInteract(e);
     }