I read the extract as shown in the image below from Vayuviya Samhita Chapter 14 of Shiva Purana:
In the verse # 9 (the highlighted one), it is said that:
He (Lord Rudra) is brilliant holding the skulls of asura Jalandhara, Brahma and Indra, his tawny hair, mustache and beard are drenched in the surging waves of Ganga.
This line is said in the praise of Lord Rudra (popularly known as Lord Shiva). I am aware that Jalandhara was a demon killed by him. Lord Brahma's one head was also cut by Lord Rudra/Shiva but I don't know of any incident where Indra's head was being cut by Lord Rudra/Shiva. Do we have any scriptures that store some story behind this?