This is mainly focusing on way to do it on iOS, since officially game is only for iOS atm, and if you are android user just use mobizen.
Lets start with free option, which is also best for personal use:
go to: https://appvalley.vip on your mobile device
This is not an official app store program so you will have to download and install it from link above (install AppValley Native). Next step is to go to Settings > Device manager > Click on untrusted developer > Say that you Trust app
Now open AppValley aplication > Click on “Discover amazing apps” picture > Type AirShou in search > select it from the list > get
From here just click on app icon >Click on “Agree” > Select “Record” > If necessary change orientation and resolution settings > Click “Next Step” > Bring up settings menu (or what ever is called) (on my device it is done by swiping from bottom to top) > Click on AirPlay mirroring > Click on AirShou(your device name)
At this point recording started > Click on Spellsouls icon > Play game!
Once you are done, Select AirShou from list of open apps and click Stop
To find recorded video Click on AirShou icon > Click on “Agree” > Click on a little movie icon on the top right corner > Select video you wish to watch
Keep in mind that you might need to reinstall this program often because of certificate
This video file will require some conversion before editing, buy if you wish to upload it to youtube without any editing that is not a problem
Another option, easier but not free (there is free trial period)
Download and install application on your PC > Start program after installation > Bring up menu on your device > Click on AirPlay mirroring > Select “Name of your PC” > Start the game > On PC mirrored window click record button > Once you are done > Click record button again > Save a file and play it when you want.
This requires stable wifi connection!!
Another mirroring program for those not satisfied with reflector is:
Same instructions as above.
Please let me know if you have any questions. Have fun and share great games you had.