I keep getting this error when trying to build the script: 

Error    1    'System.Diagnostics.Process' does not contain a definition for 'Startinfo' and no extension method 'Startinfo' accepting a first argument of type 'System.Diagnostics.Process' could be found (are you missing a using directive or an assembly reference?)    \Script\Script 1.cs    25    26    Akron Trip Sheet Day - EST

This is my code:

namespace WorkflowActivity.Scripting.Script
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Data.SqlClient;
    using System.Text;
    using System.Diagnostics;

    /// <summary>
    /// Provides one or more methods that can be run when the workflow scripting activity is performed.
    /// </summary>
    public class Script1 : ScriptClass90
    {
        /// <summary>
        /// This method is run when the activity is performed.
        /// </summary>
        protected override void Execute()
        {
            try
            {
                System.Diagnostics.Process pProcess = new System.Diagnostics.Process();
                pProcess.StartInfo.FileName = @"C:\Users\laserproven\Desktop\killOmni.bat";
                pProcess.Startinfo.UseShellExecute = false;
                pProcess.StartInfo.RedirectStandardOutput = true;
                pProcess.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
                pProcess.StartInfo.CreateNoWindow = true;
                pProcess.Start();
                pProcess.WaitForExit();
            }
            catch (Exception ex)
            {
                SetActivityTokenValue("Errors", ex.ToString());
            }
        }
    }
}

I can't figure it out for the life of me and I know it's something simple I'm missing like a namespace or something.

What version of System.Diagnostics are you referencing? You might be running into this issue.

Also, your desktop location is going to be protected and the Workflow service will not be able to access the bat file.

pProcess.StartInfo.FileName = @"C:\Users\laserproven\Desktop\killOmni.bat";

Change to something like

pProcess.StartInfo.FileName = @"C:\Temp\killOmni.bat";