Learn this, the short:

om namaścaṇḍavajrakrodhāya | om hulu hulu tiṣṭha tiṣṭha bandha bandha hana hana amṛte hūṃ phaṭ

 and after you have samadhi with it, this short dharani:

om namo ratnatrayāya | namaścaṇḍavajrapāṇaye mahāyakṣasenāpataye | tadyathā – om hara hara vajra matha matha vajra dhuna dhuna vajra daha daha vajra paca paca vajra dhara dhara vajra dhāraya dhāraya vajra dāruṇa dāruṇa vajra chinda chinda vajra bhinda bhinda vajra hūṃ phaṭ | om namaścaṇḍavajrakrodhāya | om hulu hulu tiṣṭha tiṣṭha bandha bandha hana hana amṛte hūṃ phaṭ |

From John Utah:

I know it seems long, but it’s very repetitive, super easy to learn and it contains the short mantra…

once you do this, you’ll truly have something

big time: Vajra power, healing, purification, direct insight into reality, smashing ability, cutting ability, energizing and augmenting ability…