Sauḥ सौः 

The Ekākṣarī Bīja Mantra for Vanadurgālakṣmī Ambā is sauḥ (सौः)

Prohibition Declared –

With Vāk Devī as Witness

Let this be heard with full weight:
No Tāntrika of any sampradāya, paddhati, or paramparā 
has permission to recite, chant, or even whisper a single akṣara from this mantra.

I take dharma upon myself in full consciousness, and I write this keeping Vāk Devī Herself as Sākṣī.

This is not for siddhi. This is not for tantra.
This is not to be extracted, borrowed, or reinterpreted.
This is bhakti — and bhakti alone.