Gokula’s Wonder, Kṛṣṇa’s Bhakta-vaśyatā, the Move to Vṛndāvana, and the Slaying of Vatsāsura and Bakāsura
तं वत्सरूपिणं वीक्ष्य वत्सयूथगतं हरि: । दर्शयन् बलदेवाय शनैर्मुग्ध इवासदत् ॥ ४२ ॥
taṁ vatsa-rūpiṇaṁ vīkṣya vatsa-yūtha-gataṁ hariḥ darśayan baladevāya śanair mugdha ivāsadat
Seeing the demon disguised as a calf and mingled among the herd, the Lord Hari signaled to Baladeva, “Here is another demon.” Then, as if unaware of its intent, He approached it very slowly, with an air of innocent wonder.
The import of the words mugdha iva is that although Kṛṣṇa knows everything, here He pretended that He did not understand why the demon had entered among the calves, and He informed Baladeva by a sign.
It describes Vatsāsura entering the calf-herd in disguise, and Kṛṣṇa immediately recognizing him and moving in to deal with him while alerting Balarāma.
To inform Balarāma of the disguised danger within the herd, showing their coordinated protection of Vraja even while Kṛṣṇa outwardly acted like an innocent child.
Be alert to hidden threats, but respond calmly and thoughtfully—protecting others without panic, pride, or unnecessary display.