Kartikeya is grown up, has received good training from Mahadev himself.
He is made Deva's Senapati. Indra is thinking my hope of getting Swarga back will materialize soon.
But I must think of future too, This boy Kartikeya is courageous & quite promising. We should have a long term relation. How about one of my daughter getting married to him in future. Wow what an Idea, I am great, that's why I am Devraj indra.
He goes to meet Kartikeya, thinking I must praise him, he'll like it.
Indra speaks to Kartikeya for a long time glorifying him as a great warrior. kartikeya is taught all the good qualities by Mahadev. But is not taught how to handle someone praising him. He finally starts believing everything said by Indra.
Nandi was listening this entire convo from a distance. He informs Paravti about this.
Parvati gives a strand of grass kept in a plate, tells Nandi to give it to Kartikeya & ask him to make a fort out of it. Nandi does the same.
Kartikeya is thinking how to do it? Consults indra, even he is unable to give any suggestion.
Parvati come there. kartikeya asks her mother how is it possibe to create a fort out of this grass?
Paravti says if you can be a great warrior just by hearing your praise, even without fighting a war, you can surely make a fort out of this grass. Kartikeya realises his mistake.
Indra asks Pravati can she demonstrate the same?
Parvati takes the grass in her hand, meditates & shows the entire World getting created out of it. She tells Kartikeya, this entire World is created by my Shakti, without me even you can't do anything. Always remember I am your power in the war, so if you win the war , it's actually me winning.
Enlightened Kartikeya bows down to his mother. Indra too follows him.