I gotta say I have a pretty big mind block about this and could think of two obvious examples, so I hope you guys can help me out find more of this kinda stuff. The one that actually had me thinking about this is of course, Black Sabbath's Under The Sun/Every Day Comes and Goes. That final sequence of the song is what makes it probably my favorite Sabbath song ever and one of the main reasons for Vol. 4 to be my favorite Sabbath album.
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And the second one that immediatly popped to mind is Entombed's Left Hand Path. That whole part that comes after the Phantasm homage/ripoff is so fucking great they should've just ended the album right there

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I hope I made myself clear enough about what I'm looking for. Any further examples?