योगवासिष्ठः yogavāsiṣṭhaḥ - book-1, chapter-25, verse-16

पश्चात्प्रालम्बविभ्रान्तकौमारभृतबर्हिभिः ।
नेत्रत्रयवृहद्रन्ध्रभूरिभाङ्कारभीषणैः ॥ १६ ॥

paścātprālambavibhrāntakaumārabhṛtabarhibhiḥ ,
netratrayavṛhadrandhrabhūribhāṅkārabhīṣaṇaiḥ 16

16. paścāt prālamba-vibhrānta-kaumāra-bhṛta-barhibhiḥ
netra-traya-vṛhat-randhra-bhūri-bhāṅkāra-bhīṣaṇaiḥ

16. paścāt prālamba-vibhrānta-kaumāra-bhṛta-barhibhiḥ
netra-traya-vṛhat-randhra-bhūri-bhāṅkāra-bhīṣaṇaiḥ

16. Behind her, with dangling peacocks held by bewildered Kumāras, and with terrifying, abundant roars emanating from the vast apertures of her three eyes.

Words meanings summery:

• पश्चात् (paścāt) - behind (the Goddess). (behind, afterwards, in the west)

• प्रालम्ब-विभ्रान्त-कौमार-भृत-बर्हिभिः (prālamba-vibhrānta-kaumāra-bhṛta-barhibhiḥ) - by peacocks that are held by bewildered Kumāras and are dangling. (by peacocks held by bewildered Kumāras (who are) hanging down)

• नेत्र-त्रय-वृहत्-रन्ध्र-भूरि-भाङ्कार-भीषणैः (netra-traya-vṛhat-randhra-bhūri-bhāṅkāra-bhīṣaṇaiḥ) - by sounds/entities made terrifying by abundant roars from the vast apertures of her three eyes. (by those terrifying with abundant roars from the great holes of three eyes)

Words meanings and morphology

पश्चात् (paścāt) - behind (the Goddess). (behind, afterwards, in the west)

(indeclinable)

प्रालम्ब-विभ्रान्त-कौमार-भृत-बर्हिभिः (prālamba-vibhrānta-kaumāra-bhṛta-barhibhiḥ) - by peacocks that are held by bewildered Kumāras and are dangling. (by peacocks held by bewildered Kumāras (who are) hanging down)

(noun)

Instrumental, masculine, plural of prālamba-vibhrānta-kaumāra-bhṛta-barhi

prālamba-vibhrānta-kaumāra-bhṛta-barhi - peacocks held by bewildered Kumāras, (the peacocks being) hanging down

Compound type : bahuvrihi (prālamba+vibhrānta+kaumāra+bhṛta+barhi)

• prālamba – hanging down, pendulous
  adjective (masculine)
  From pra + lamb (to hang)
  Prefix: pra
  Root: lamb (class 1)
• vibhrānta – bewildered, confused, roaming about
  adjective (masculine)
  Past Passive Participle
  From vi + bhrām (to wander, to be confused)
  Prefix: vi
  Root: bhrām (class 1)
• kaumāra – youthful, belonging to Kumāra (Kartikeya)
  adjective (masculine)
  Derived from Kumāra
• bhṛta – held, borne, supported
  adjective (masculine)
  Past Passive Participle
  From root bhṛ (to bear, hold)
  Root: bhṛ (class 3)
• barhi – peacock
  noun (masculine)

Note: Describes something accompanying the goddess or part of her dreadful retinue/aspect.

नेत्र-त्रय-वृहत्-रन्ध्र-भूरि-भाङ्कार-भीषणैः (netra-traya-vṛhat-randhra-bhūri-bhāṅkāra-bhīṣaṇaiḥ) - by sounds/entities made terrifying by abundant roars from the vast apertures of her three eyes. (by those terrifying with abundant roars from the great holes of three eyes)

(adjective)

Instrumental, masculine, plural of netra-traya-vṛhat-randhra-bhūri-bhāṅkāra-bhīṣaṇa

netra-traya-vṛhat-randhra-bhūri-bhāṅkāra-bhīṣaṇa - terrifying with abundant roars from the great apertures of three eyes

Compound type : bahuvrihi (netra-traya+vṛhat-randhra+bhūri-bhāṅkāra+bhīṣaṇa)

• netra-traya – three eyes
  noun (neuter)
• vṛhat-randhra – great hole, vast aperture
  noun (neuter)
• bhūri-bhāṅkāra – abundant roaring, many roars
  noun (masculine)
• bhīṣaṇa – terrifying, dreadful
  adjective (masculine)
  Causer of fear (present participle)
  From root bhī (to fear) with suffix -ṣaṇa
  Root: bhī (class 3)

Note: Agrees with the previous instrumental plural form, or implicitly with an understood 'by (these) terrifying things/sounds'.