महाभारतः mahābhārataḥ - book-7, chapter-35, verse-15

प्रवर्तमाने संग्रामे तस्मिन्नतिभयंकरे ।
द्रोणस्य मिषतो व्यूहं भित्त्वा प्राविशदार्जुनिः ॥१५॥

15. pravartamāne saṁgrāme tasminnatibhayaṁkare ,
droṇasya miṣato vyūhaṁ bhittvā prāviśadārjuniḥ.

15. pravartamāne saṅgrāme tasmin atibhayaṃkare
droṇasya miṣataḥ vyūham bhittvā prāviśat ārjuniḥ

15. tasmin atibhayaṃkare pravartamāne saṅgrāme
droṇasya miṣataḥ ārjuniḥ vyūham bhittvā prāviśat

15. While that extremely dreadful battle was raging, the son of Arjuna (Abhimanyu) penetrated the formation (vyūha), even as Drona watched.

Words meanings summery:

• प्रवर्तमाने (pravartamāne) - while proceeding, while raging

• सङ्ग्रामे (saṅgrāme) - in the battle, in the war

• तस्मिन् (tasmin) - in that, in that one

• अतिभयंकरे (atibhayaṁkare) - in the extremely dreadful, in the very terrifying

• द्रोणस्य (droṇasya) - of Drona

• मिषतः (miṣataḥ) - of him watching, of him looking on

• व्यूहम् (vyūham) - the formation, the array

• भित्त्वा (bhittvā) - having broken, having split

• प्राविशत् (prāviśat) - entered

• आर्जुनिः (ārjuniḥ) - son of Arjuna, Abhimanyu

Words meanings and morphology

प्रवर्तमाने (pravartamāne) - while proceeding, while raging

(participle)

Locative, masculine, singular of pravartamāna

pravartamāna - proceeding, raging, active, current

Present Middle Participle

Derived from root vṛt (class 1) with prefix pra and the present middle participle suffix.

Prefix: pra

Root: vṛt (class 1)

सङ्ग्रामे (saṅgrāme) - in the battle, in the war

(noun)

Locative, masculine, singular of saṅgrāma

saṅgrāma - a battle, war, fight

तस्मिन् (tasmin) - in that, in that one

(pronoun)

Locative, masculine, singular of tad

tad - that, he, she, it

अतिभयंकरे (atibhayaṁkare) - in the extremely dreadful, in the very terrifying

(adjective)

Locative, masculine, singular of atibhayaṃkara

atibhayaṁkara - very dreadful, terrifying, horrible

Compound type : karmadhāraya (ati+bhayaṃkara)

• ati – over, beyond, exceeding, very
  indeclinable
• bhayaṃkara – terrifying, dreadful
  adjective (masculine)

द्रोणस्य (droṇasya) - of Drona

(proper noun)

Genitive, masculine, singular of droṇa

droṇa - Drona (a famous teacher of archery, a character in the Mahābhārata)

मिषतः (miṣataḥ) - of him watching, of him looking on

(participle)

Genitive, masculine, singular of miṣat

miṣat - watching, looking, perceiving

Present Active Participle

Derived from root miṣ (class 1) with the present active participle suffix.

Root: miṣ (class 1)

व्यूहम् (vyūham) - the formation, the array

(noun)

Accusative, masculine, singular of vyūha

vyūha - an array, military formation, arrangement

भित्त्वा (bhittvā) - having broken, having split

(indeclinable)

Absolutive (Gerund)

Formed from root bhid (class 7) with the suffix -tvā.

Root: bhid (class 7)

प्राविशत् (prāviśat) - entered

(verb)

3rd person , singular, active, imperfect (laṅ) of viś

Prefix: pra

Root: viś (class 6)

आर्जुनिः (ārjuniḥ) - son of Arjuna, Abhimanyu

(proper noun)

Nominative, masculine, singular of ārjuni

ārjuni - son of Arjuna (a patronymic, referring to Abhimanyu)