Complex sentence: After sending out several demo tapes, he was discovered and signed by the label Horrorkore Entertainment, and worked with his mentor MC Basstard on their collabo mixtape "Horrorkore Mixtape Teil 1".
Split into simpler sentences: After sending out several demo tapes, the label Horrorkore Entertainment discovered and signed him. Afterwards Taha worked with his mentor MC Basstard on their collabo mixtape "Horrorkore Mixtape Teil 1".