diff --git a/worldedit-core/src/main/java/com/sk89q/worldedit/internal/util/DeprecationUtil.java b/worldedit-core/src/main/java/com/sk89q/worldedit/internal/util/DeprecationUtil.java
new file mode 100644
index 000000000..1376383c7
--- /dev/null
+++ b/worldedit-core/src/main/java/com/sk89q/worldedit/internal/util/DeprecationUtil.java
@@ -0,0 +1,97 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.internal.util;
+
+import com.google.common.base.Joiner;
+import com.google.common.base.Throwables;
+
+import java.lang.reflect.Method;
+import java.util.stream.Stream;
+
+public class DeprecationUtil {
+
+    private DeprecationUtil() {
+    }
+
+    /**
+     * Verify that one of the two functions is overridden. Caller method must be the new method,
+     * annotated with {@link NonAbstractForCompatibility}.
+     *
+     * @param implementingClass the result of calling {@link Object#getClass()}
+     */
+    public static void checkDelegatingOverride(Class<?> implementingClass) {
+        // pull the information about the caller
+        StackTraceElement caller = Throwables.lazyStackTrace(new Throwable()).get(1);
+        // find the matching caller method
+        Method callingMethod = getCallingMethod(caller);
+        NonAbstractForCompatibility annotation =
+            callingMethod.getAnnotation(NonAbstractForCompatibility.class);
+        // get the deprecated method
+        Method deprecatedMethod;
+        try {
+            deprecatedMethod = implementingClass.getMethod(
+                annotation.delegateName(), annotation.delegateParams()
+            );
+        } catch (NoSuchMethodException e) {
+            throw new AssertionError(
+                "Missing method referenced by " + NonAbstractForCompatibility.class, e
+            );
+        }
+        // Check if the deprecated method was overridden. If the declaring class is the caller's
+        // class, then it wasn't. That means that the caller method (i.e. the new method) should be
+        // overridden by the implementing class.
+        // There's no need to check if the new method has been overridden, since the only other
+        // way this could be reached is if someone calls `super.xyz`, which they have no reason to.
+        if (deprecatedMethod.getDeclaringClass().getName().equals(caller.getClassName())) {
+            throw new IllegalStateException("Class " + implementingClass.getName()
+                + " must override " + methodToString(callingMethod));
+        }
+    }
+
+    private static Method getCallingMethod(StackTraceElement callerInfo) {
+        Method[] declaredMethods;
+        try {
+            declaredMethods = Class.forName(callerInfo.getClassName()).getDeclaredMethods();
+        } catch (ClassNotFoundException e) {
+            throw new AssertionError("Caller class missing?", e);
+        }
+        for (Method declaredMethod : declaredMethods) {
+            if (declaredMethod.isAnnotationPresent(NonAbstractForCompatibility.class) &&
+                declaredMethod.getName().equals(callerInfo.getMethodName())) {
+                return declaredMethod;
+            }
+        }
+        throw new IllegalStateException("Failed to find caller method " +
+            callerInfo.getMethodName() + " annotated with " + NonAbstractForCompatibility.class);
+    }
+
+    private static String methodToString(Method method) {
+        StringBuilder builder = new StringBuilder(method.getDeclaringClass().getCanonicalName())
+            .append('.')
+            .append(method.getName())
+            .append('(');
+        Joiner.on(", ").appendTo(builder, Stream.of(method.getParameterTypes())
+            .map(Class::getSimpleName)
+            .iterator());
+        builder.append(')');
+        return builder.toString();
+    }
+
+}
diff --git a/worldedit-core/src/main/java/com/sk89q/worldedit/internal/util/NonAbstractForCompatibility.java b/worldedit-core/src/main/java/com/sk89q/worldedit/internal/util/NonAbstractForCompatibility.java
new file mode 100644
index 000000000..f67131d73
--- /dev/null
+++ b/worldedit-core/src/main/java/com/sk89q/worldedit/internal/util/NonAbstractForCompatibility.java
@@ -0,0 +1,57 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.internal.util;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * The annotated method is only non-{@code abstract} for compatibility with old subclasses,
+ * and will be made {@code abstract} in the next major version of WorldEdit.
+ *
+ * <p>
+ * Any new subclasses <em>must</em> override the annotated method, failing to do so will result in
+ * an exception at runtime.
+ * </p>
+ */
+@Documented
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface NonAbstractForCompatibility {
+
+    // Note that this annotation only functions properly if no other method in the same class
+    // shares the name of the annotated function AND is also annotated with this annotation.
+    // Otherwise, we cannot uniquely determine the calling method via reflection hacks.
+    // This could be changed, but it's not currently necessary.
+
+    /**
+     * The name of the method delegated to by the annotated method.
+     */
+    String delegateName();
+
+    /**
+     * The parameter types of the method delegated to by the annotated method.
+     */
+    Class<?>[] delegateParams();
+
+}