THREAD

3 Śūla-s of Śiva's Trident represent the 3 female divinities (śakti-s) of esoteric Śaiva paramparā of Trika -

Parā, Aparā and Parāpara.

Here is the tremendously sacred & energetic Ahvāhanam (Invocation) to the Tridevī of Tantra that is done once guided into by the Gurū:

नौमि चित्प्रतिभां देवीं परां भैरवयोगिनीं ।
मातृमानप्रमेयांशशूलाम्बुजकृतास्पदाम् ॥

naumi citpratibhāṁ devīṁ parāṁ bhairavayoginīm ।
mātṛmānaprameyāṁśaśūlāmbujakṛtāspadām ॥

Abhinavaguptapādācārya invokes her and says:

"I bow down before the parā (ultimate) energy, which is cit-pratibhā (light of consciousness) & is one with the ultimate - Bhairava (Śiva); that energy which is established in lotus āsana within the lotuses on three Śūla-s or spikes.

These three Lotuses are of three points:
One of subjective consciousness
the other of cognitive consciousness
and the other of objective consciousness.

"On these three sharp spikes is seated that Bhairava yoginī, the supreme energy of Śiva, I bow down to That - Parādevī."

Then Guptapādācārya goes on to invoke Aparā Devī:

नौमि देवीं शरीरस्थां नृत्यतो भैरवाकृते ।
प्रावृणमेघघनव्योमविद्युल्लेखाविलासिनीं ॥

naumi devīṁ śarīrasthāṁ nṛtyato bhairavākṛte ।
prāvṛṇmeghaghanavyomavidyullekhāvilāsinīm ॥

I bow to Aparā, the second energy of Śiva, who is situated in material bodies, and gross body of Bhairava the dancer, who is shining just like the lightening through dense clouds of rainy season. Light of objective world; the form of Śiva Caitanya.

dīptajyotiśchaṭāpluṣṭabhedabandhatrayaṁ sphurat ।
stājjñānaśūlaṁ satpakṣavipakṣotkartanakṣamam ॥

Triśūla of Śiva–although it is filled with will, knowing, & action (Iccha, Jñāna, Krīyā) it has predominance of Jñāna śūlaṁ–let that remain in such a way that it destroys opposites in supreme state of jagat-ānanda. And let that śūla destroy all the 3 bondages by its dīpta jyoti.