Guide on multi-clienting [no 3rd party software] [old/new login compatible]

Simple guide on multi-clienting

Introduction
The client "protects" us from opening multiple instances by simply placing a "lockfile" inside the work directory.
We can easily trick the client by deleting it
I originally thought Riot was gonna "fix" that by adding code that checks whether another client is already running but that didn't happen in the past 6 months so I assume it's safe to say this method will be working for a little longer

New Log-in system - Riot Client
With the riot client things have changed a little bit, the riot client actually checks whether another riot client is still running.
Fortunately this isn't too bad since it's just used for initial authentication and doesn't need to be present once the League client is opened

Conclusion
It is possible to open multiple clients with only 4 (technically 3) lines of "code" (batch / windows command line)
The code I included (see below) works with the old and new log-in system and doesn't need to be adjusted.

Creating a starter

• Open an editor of your choice
• Copy-paste the code below into your editor
• Select Save as and navigate to your League of Legends folder (C:\Riot Games\League of Legends)
• Call it something like start.bat (important is the .bat extension, on notepad you might need to switch the file type to all files (*.*))
• Navigate to the directory you've placed the file
• Double click it to verify League/Riot Client opens
• Log in to your first account AND make sure the League client opens
• Double click the file again to verify another client opens
• (optional) Right click the starter you've created and send it to your desktop
• (optional) Go to your desktop and change the icon of your start link to whatever League icon you prefer