Why did Kṛṣṇa use tricks in the Kurukṣetra war?

the epic presents a war where rules had already collapsed — and it lets Kṛṣṇa be questioned for it.

Several Kaurava commanders fall through stratagems Kṛṣṇa advises: Bhīṣma is faced with Śikhaṇḍī, Droṇa is told “Aśvatthāmā is dead” (an elephant of that name), Karṇa is struck while freeing his chariot wheel, and Duryodhana is hit on the thigh. Readers rightly ask how God can bend the rules.

The epic gives several answers. The Kauravas had already broken the code of war — most cruelly in surrounding and killing the young Abhimanyu. Kṛṣṇa argues that when adharma is protected by rules, clinging to the letter of the rules lets evil win; this is the idea of dharma-sūkṣma, the subtlety of dharma. Devotees add that each of these warriors had chosen the wrong side despite knowing better.

But the Mahābhārata does not hide the cost. Gāndhārī, grieving all her sons, curses Kṛṣṇa, and he accepts the curse. The epic invites us to think, not just to approve.

Source: Mahābhārata, Droṇa, Karṇa, Śalya and Strī Parvas · Dharma-sūkṣma: the subtlety of dharma

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