A piece of tantric ritual

I'll give here a bit of the ritual from Vajrabhairavatantra. This ritual extends in the entire second chapter but I'll translate only two phrases.

Here is the Sanskrit text:
..............
tatredaṃ karma yadā sādhayitukāmaḥ tadā śmaśānakarpaṭe viṣarudhireṇa lavaṇarājikānimbadhutturakarasena idaṃ ṣoḍaśakoṣṭhaṃ mahāvajrabhairavacakraṃ bṛhatkākasya pakṣeṇa lekhanyā [narāsti lekhanyā] vā dakṣiṇābhimukho nagno muktaśikho bhūtvā mahiṣamukhayogena likhet |
...............
pūrvokta saha dravyeṇa¹ (pūrvoktadravyeṇa saha) kākocchiṣṭena vairocanena śmaśānakarpaṭe stambhayitvā(tib. abhyaṅgaya) tatra likhet cakraṃ pūrvoktavidhānena
...............

Now the translation:

Next this rite. When the performer desire then on the garments of the cremation ground, using blood poisoned by a juice of salt, mustard(sk. rājikā, lat Sinapis Ramosa), thorn apple (dhusturaka/Datura), neem (nimba), with a quill from a big crow or a pen, being naked, with the hair in disorder and facing south he should draw this 16 room wheel of the great vajrabhairava.
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Having rubbed [himself] with the substance previously specified, food remains of a crow, urine (sk. vairocana code name for urine) on the pyre garments he should draw there the wheel(cakra) with the disposition previously described.


Note 1:
"pūrvoktadravya" here might be "kaṭutaila" which might mean 'stinky oil' or 'sour oil' cf MW 'white mustard'. However Bulcsu Siklos translated this form Tibetan as "warm butter".