taṁ vatsa-rūpiṇaṁ vīkṣya
vatsa-yūtha-gataṁ hariḥ
darśayan baladevāya
śanair mugdha ivāsadat
tam - unto the demon; vatsa-rūpiṇam - assuming the form of a calf; vīkṣya - seeing; vatsa-yūtha-gatam - when the demon entered the group of all the other calves; hariḥ - the Supreme Personality of Godhead, Kṛṣṇa; darśayan - indicating; baladevāya - unto Baladeva; śanaiḥ - very slowly; mugdhaḥ iva - as if He did not understand anything; āsadat - came near the demon.
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.