On this process you will need an external Hard drive with atleast 10GB free space. You will also need of course a computer with a working League of Legends installed on that PC. On This guide we will be using a windows 10 PC – I am not sure if this will work on other operating system
Copy Garena folder on OS(C) and Garena on Program files (x68)
Make a New folder for each Garena files on your External hard drive and paste it there.
You will need to download a New Garena on their Website on your new PC or Laptop Then Install
Paste the Garena(program files) folder from your external hdd to your laptop's program files (x86) - Skip all files with Same Name (SKIP THESE FILES)
Paste the Garena Folder (from C) from your external HDD to your New Laptop's OS(C)
Open your Garena program- Open League of Legends - Click Install
Change Destination Folder
Select Games -- This PC > OS(C) > Garena >> make sure to Highlight games - Select folder
CONGRATS!! YOUR DONE!!!!
You can now Play League of Legends on your New PC without having to Download the Whole LOL file again