In Jain karma theory, no single karma alone is usually said to “take” a soul into Nigod. It is the combined bondage and fruition of karmas, especially:

• Mohaniya karma — because intense delusion, attachment, anger, pride, deceit, and greed keep the soul in a very low state.
• Nāma karma — because it determines the body-form and the specific birth-condition.
• Āyu karma — because it fixes the lifespan in that birth.

So, Nigod gati is generally understood as the result of very heavy karmic bondage, especially Mohaniya karma, supported by Nāma and Āyu karma.

In simple words: extreme ignorance, passions, and हिंसा-based karmic bondage can lead a soul to Nigod.

If you want, I can also explain Nigod in Jain cosmology in simple terms.