I decided to create a clean tutorial for those who want to root their HTC Desire 816! I will be editing it as new improvements appear.
Disclaimer - This will void your warranty and unlocking bootloader will also erase all your data in internal storage! 
1. Install HTCwhy is desire 610 linked to this thread? Sync Manager
(Required because it packs in the drivers essential for PC to recognize the device)
http://www.htc.com/in/software/htc-sync-manager/
2. Unlock your phone's bootloader
Follow the steps listed here :
http://www.htcdev.com/bootloader
You need to select device model as "HTC One"(Don't worry, it all follows almost same steps)
3. Download and Install a custom recovery!
> Download your recovery exe file(I recommend it so that it doesn't causes any troubles for newbies) from
here.
> Boot you phone into fastboot and run the exe file, it will install the recovery(CWM 6.0.4.7 as of the date of writing).
> Boot into recovery by selecting HBOOT(Select using Power button and scroll via volume keys)
4. Download and flash SuperSU!
> Download the latest SuperSU zip file from
here!
> Place it in the root of your sd card(Internal or External, your choice)
> Boot into recovery and select "Install Zip from SD Card".
> Select where you kept the flashable zip(Internal/External storage)
> Select the file when it shows all your files and then select "Yes" to let it flash.
> After flashing completes, reboot!
> Use the wp_mod.ko module from
here!
> ?
> Profit! You finally have a rooted HTC Desire 816! Yay!
Credits -
@kinghunki for the initial recovery images.
