So reflection was awful to work with. I'm moving on to a new method...

using an Interface full of useful NMS methods. I'm still using
reflection, but only when absolutely needed.
I'm also working on a new and better implementation for NBT Lists.
Made NBT Lists and NBT Compounds serializable (can be saved in variables
through restarts), needs testing.

src/me/TheBukor/SkStuff/effects/EffGZipFile.java

@@ -0,0 +1,56 @@
+package me.TheBukor.SkStuff.effects;
+
+import java.io.EOFException;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.zip.GZIPOutputStream;
+
+import javax.annotation.Nullable;
+
+import org.bukkit.event.Event;
+
+import ch.njol.skript.lang.Effect;
+import ch.njol.skript.lang.Expression;
+import ch.njol.skript.lang.SkriptParser.ParseResult;
+import ch.njol.util.Kleenean;
+
+public class EffGZipFile extends Effect {
+	private Expression<String> filePath;
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public boolean init(Expression<?>[] expr, int matchedPattern, Kleenean arg2, ParseResult result) {
+		filePath = (Expression<String>) expr[0];
+		return true;
+	}
+
+	@Override
+	public String toString(@Nullable Event e, boolean debug) {
+		return "create GZipped file at " + filePath.toString(e, debug);
+	}
+
+	@Override
+	protected void execute(Event e) {
+		File newFile = new File(filePath.getSingle(e));
+		/*
+		if (!newFile.exists()) {
+			try {
+				newFile.createNewFile();
+			} catch (IOException ex) {
+				ex.printStackTrace();
+			}
+		}
+		*/
+		try {
+			new GZIPOutputStream(new FileOutputStream(newFile)).close();
+		} catch (FileNotFoundException ex) {
+			ex.printStackTrace();
+		} catch (IOException ex) {
+			if (!(ex instanceof EOFException)) {
+				ex.printStackTrace();
+			}
+		}
+	}
+}