O descendant of the Bharata lineage! Deeds performed through intelligence are the best, those performed with the arms are medium, and those performed by bearing loads with the thighs are the worst.
- 35, Prajagara parva, Mahabharata.
Krishna used his intelligence to counter formidable opponents and save the Yadavas and Pandavas alike.
Kalayavana
Kalayavana had a boon from Shiva of invincibility against the Yadavas. Krishna tricked him to chase after him by pretending to flee. Krishna lured the Yavana king into a cave where king Muchukunda was sleeping. Muchukunda had a boon from the devas that anyone who disturbs his sleep would be burned down. Krishna fooled Kalayavana into disturbing Muchukunda and as a result got burnt to ashes.
Jarasandha
Jarasandha had the largest army in the entire country and most of the kings were his allies. Krishna skillfully avoided a direct confrontation between Jarasandha's army and Indraprastha’s army by going to Magadha in disguise with Bhima and Arjuna and then getting Jarasandha killed in a one on one wrestling match with Bhima. Krishna knew that Jarasandha due his pride and arrogance will not back down from a challenge -
If that lord of men is confronted by the three of us alone, there is no doubt that he will engage one of us in a duel. Out of contempt for the worlds and his pride in himself, he will certainly challenge Bhimasena to a duel.
- 18, Jarasandha Vadha parva, Mahabharata.
Thus Krishna averted a huge war between Magadha and Indraprastha and killed Jarasandha by using his own pride against him.
Vasavi Shakti
Karna had Indra's Vasavi Shakti with a boon of infallibility. Krishna saved Arjuna by keeping him away from Karna as much as possible, confused Karna's mind making him forget about the astra every day and then finally diverting the missile to Ghatotkacha. Krishna thus wasted the divine missile and got rid of the wicked Ghatotkacha at the same time.
Keshava has always protected Kounteya Arjuna. In the battle, that is the reason he didn't allow him to be stationed before the son of the suta. Achyuta stationed other supreme rathas there. O lord! He acted so that the infallible spear might become fallible.
‘Sanjaya said, “O king! The slayer of Madhu knew what Karna desired to do. The immensely intelligent Janardana instructed the immensely valorous Ghatotkacha, lord of the rakshasas, to engage in that duel. The intention was to make the infallible weapon useless.
- 157, Drona Vadha parva, Mahabharata.
Drona
This was the the only time Krishna specifically made out a strategy to bring down a Kaurava warrior. Seeing Drona was especially dangerous on the 15th day, Lord Krishna came up with the strategy of demoralising him by spreading the rumour of Ashwatthama’s death. Drona in despair abandoned his weapons and is consequently killed by Dhrishtadyumna.