Complex sentence: The tathagatagarbha sutras, on occasion, speak of the ineffable skandhas of the Buddha (beyond the nature of worldly skandhas and beyond worldly understanding), and in the Mahayana Mahaparinirvana Sutra the Buddha tells of how the Buddha's skandhas are in fact eternal and unchanging.
Split into simpler sentences: The tathagatagarbha sutras, on occasion, speak of the ineffable skandhas of the Buddha (beyond the nature of worldly skandhas and beyond worldly understanding). In the Mahayana Mahaparinirvana Sutra the Buddha tells of how the Buddha's skandhas are in fact eternal and unchanging.