(If you want to go directly to summoning an entity to aid you - skip this section and go directly to section 13 onwards).
Lankini is a powerful Rakshasa demon that guarded the doors/portals to the Rakshasa Tala (dimension). In Hindu Aaiyyanist theology She was once the gatekeeper of the Brahma Loka but became arrogant in her duties and treated her companions badly, so was sent down to guard the Rakshasa Tala. In Aaiyyanist Hinduism there is not really such thing as good or evil as we are all part of Brahman. We believe in positive and negative energy. Positive energy stems from acts such as love and forgiveness. Negative energy comes from selfishness, greed and arrogance. Thus Brahma decided to send Lankini where she belonged. In traditional Hinduism the act of exile was said to be a curse that could only be broken if Lankini was defeated in battle by a monkey (Hanuman) but in Dravidian Aaiyyanist thought Lankini was sent to be the guardian of the Rakshasa realm by choice and so any battle fought would have no standing on her position in the cosmic standing.
Tantric Aaiyyanists know that in order to break down the Talas to Brahman one needs to go through the Rakshasa Tala and so Lankini is very important in this regard. She is the guardian of this portal and with Dantin and Asura Kalanemi they make a trinity of guardians of evil that can open the doors to more powerful Gods/Demons such as Kali and Siva himself. Remember in Aaiyyanism there is no such thing really as 'evil and good', only positive and negative resonant energies. Once the being becomes powerful enough such as Kali and Siva they have mastery of both negative and positive and to our eyes can be considered as nether God nor Demon. Siva the God of Destruction (of the ego and of the Talas and Lokas) can bring us back to unity with Brahman and as such in Dravidian Aaiyyanist terms is the most powerful of the Hindu Trinity. In Hindu Aaiyyanism, Creation (Brahma) is a simple act of breaking from Brahman, remaining separate from Brahman (preserving/protecting) is the realm of Vishnu, but merging back with Brahman in a act of destruction to kill the ego self as well as destroy all the realms (Talas/Lokas) to fuse into Oneness - that is the highest gift of Siva.
How does Lankini fit into all of this. We already know that in this plane of reality Gatisaman and Adhavena were the inscribers in this realm. Likewise to breakdown the various dimensions from this to Brahman one needs the help of intermediaries in other Talas (dimensions). In the negative sphere, Lankini, Dantin and Kalanemi are those intermediaries.
Hindu Aaiyyanists have historically known that Vinayaka Dantin is considered a powerful demon that has mastery over the negative energies, but it also requires Rakshasa Lankini and Asura Kalanemi to be able to direct and control that energy. Lankini is in fact the founder/Queen and Guardian of the intermediate dimension (Rakshasa Tala) between our realm and Brahman that we must pass through if we use the Tala route. These three powerful demons are required in order to break the boundaries between the false reality and the true one and Her (Lankini's) role is pivotal in that we can invoke her to stabilise the negative energy in our plane and others.
Tantric Aaiyyanists usually call on Lankini to aid them in their control of negative energy especially if they need a large amount of it. When you converse with the lesser demons in this book there will be a time when you require more resonant energy, and at that time you will need the aid of Rakshasa Lankini. To summon her you can follow the instructions in section 17.