Finally...I have successfully installed TWRP & MAGISK in my S7 Edge Exynos at first it was just boot looping for the reason that my DATA isn't wiped by twrp successfully so I switched off the mobile phone and rebooted on custom recovery and do the data wipe then installed Magisk then boot up to system im using stock Oreo firmware as I was not feeling good if I'll be successful. Good thing lady luck was with me :fingers-crossed: thanks again XDA !