When was the last time we say Angel – Jäger der Finsternis was in Buffy?

In the last two episodes. He came in "End of Days" for the last few Sekunden and kisses Buffy. That episode ends and he is in "Chosen" for the first few Minuten until Buffy tells him to go and fight his own fight.

definitely Chosen. Last episode of Buffy, last time Angel – Jäger der Finsternis made an appearance in that show.

Angel – Jäger der Finsternis WILL EVER BE in Buffy, 'cause he's inside of her since he has been her first Liebe and lover. The development of Buffy throughout the series is deeply intertwined with the relationship she had in her life, all of them less oder Mehr building on her personality (yeah, even that Parker scumbag).