DevCmd and class name should match.

src/engine/devcmd/cmds/MineActiveCmd.java

@@ -0,0 +1,67 @@
+// • ▌ ▄ ·.  ▄▄▄·  ▄▄ • ▪   ▄▄· ▄▄▄▄·  ▄▄▄·  ▐▄▄▄  ▄▄▄ .
+// ·██ ▐███▪▐█ ▀█ ▐█ ▀ ▪██ ▐█ ▌▪▐█ ▀█▪▐█ ▀█ •█▌ ▐█▐▌·
+// ▐█ ▌▐▌▐█·▄█▀▀█ ▄█ ▀█▄▐█·██ ▄▄▐█▀▀█▄▄█▀▀█ ▐█▐ ▐▌▐▀▀▀
+// ██ ██▌▐█▌▐█ ▪▐▌▐█▄▪▐█▐█▌▐███▌██▄▪▐█▐█ ▪▐▌██▐ █▌▐█▄▄▌
+// ▀▀  █▪▀▀▀ ▀  ▀ ·▀▀▀▀ ▀▀▀·▀▀▀ ·▀▀▀▀  ▀  ▀ ▀▀  █▪ ▀▀▀
+//      Magicbane Emulator Project © 2013 - 2022
+//                www.magicbane.com
+
+
+package engine.devcmd.cmds;
+
+
+import engine.devcmd.AbstractDevCmd;
+import engine.gameManager.BuildingManager;
+import engine.objects.AbstractGameObject;
+import engine.objects.Building;
+import engine.objects.Mine;
+import engine.objects.PlayerCharacter;
+
+/**
+ *
+ */
+public class MineActiveCmd extends AbstractDevCmd {
+
+	public MineActiveCmd() {
+        super("mineactive");
+    }
+
+	@Override
+	protected void _doCmd(PlayerCharacter pcSender, String[] args,
+			AbstractGameObject target) {
+		Building mineBuilding = BuildingManager.getBuilding(target.getObjectUUID());
+		if (mineBuilding == null)
+			return;
+
+		Mine mine = Mine.getMineFromTower(mineBuilding.getObjectUUID());
+		if (mine == null)
+			return;
+
+		String trigger = args[0];
+		switch (trigger){
+		case "true":
+			mine.handleStartMineWindow();
+			Mine.setLastChange(System.currentTimeMillis());
+			break;
+		case "false":
+			mine.handleEndMineWindow();
+			Mine.setLastChange(System.currentTimeMillis());
+			break;
+		default:
+			this.sendUsage(pcSender);
+			break;
+
+		}
+	}
+
+	@Override
+	protected String _getUsageString() {
+        return "' /mineactive true|false";
+	}
+
+	@Override
+	protected String _getHelpString() {
+        return "Temporarily add visual effects to Character";
+	}
+
+}