The slaying of Ghatotkacha:
Quoting Krishna's words from KMG (Ghatotkacha-badha Parva):
Hidimva and Vaka and Kirmira have all been slain by Bhimasena. All those Rakshasas were endued with might equal to that Ravana and all of them were destroyers of Brahmanas and sacrifices. Similarly, Alayudha, possessed of large powers of illusion, had been slain by Hidimva's son. Hidimva's son also, I have slain by the employment of means, viz., through Karna with his dart. If Karna had not slain him with his dart in great battle, I myself would have had to slay Bhima's son Ghatotkacha. From desire of benefiting you, I did not slay him before. That Rakshasa was inimical to Brahmanas and sacrifices. Because he was a destroyer of sacrifices and of a sinful soul, therefore hath he been thus slain. O sinless one, by that act as a means, the dart given by Sakra, hath also been rendered futile. O son of Pandu, they that are destroyers of righteousness are all slayable by me. Even that is the vow made by me, for establishing righteousness.
- Employ Ghatotkacha to kill Alayudha
- Instigate Ghatotkacha to fight Karna during the night so that either of them gets killed.
- If Ghatotkacha kills Karna, it gives the Pandavas a huge advantage.
- If Karna kills Ghatotkacha, he will no longer be able to use the dart, his trump card against Arjuna.
Poor Ghatotkacha, who foresees his death but unaware of Krishna's good intentions, assumes a gigantic size and falls on a portion of the Kaurava army, thereby crushing one .
In short, Krishna made a out of Ghatotkacha!