There are many Legends about many different Ruesi. One of the Ruesi to be found so often mentioned in Thai Mythology, is Por Gae Ruesi Thai Fai.
The legend of Higher beings has been told in different Mythologies and Cultures around the world.
In Thailand there are also various legends of "Pu Wisaed"
or Ruesi , Arhants or Yogis.
These Ruesi are said to have posessed various powers, such as;
knowledge of Herbal medicines, minerals, magical invocations, and
supernatural abilities such as floating, teleportation and mindreading
powers.
These beings with special powers are reputed to have lived recluse
lives in the forest, on mountains, or in caves; practising meditative
skills and mental development using secret methods passed on from mouth
to ear by their foregoers/masters.
Most tradtional Ruesi respect the Pantheon of Higher Beings according to the Brahmin tradition.
Namely; Lord Brahma Shiva and Vishnu.
Most Ruesi practice the development of power and evocation/invocation
( gasin/peng กสิณ หรือ เพ่ง)
the word peng means in principle to "stare", but in this case it
really means to insert or transform matter or substance whether it be
physical element or spiritual element.
Bpataweegasin (ปฐวีกสิณ), for example means to project earth element into a target/object. Bpatawee (ปฐวี) means Earth.
Aabpoegasin
(อาโปกสิณ) means to stare/project water (aabpe means water element) -
one technique used for example to master the evocation of water element
would be to obtain clear water, such as rain water for example, and
fill a clean container with it.(not to the brim)
After this meditate and stare ate the water until the inner experience of absorbtion with water occurs
once mastered the use of this mind evocation in conjunction with the
kata "Aabpoegasinang" (อาโปกสิณัง) will enable the master to evoke
water element into another element , such as earth. This is in fact the
technique used for Kong Grapan/maha ud, which is the effect of making a
bullet harmless or a gun refuse to go off when the trigger is
pulled.The solid (earth element0 object is turned into a soft watery
element, and thus becomes harmless
It is possible to evoke not only elements such as earth water fire and air, but also colors.
Through Yogic mind development and the use of gasin and amnaj (power -
อำนาจ), the Ruesi have developed abilities such as being able to walk
on the surface of the water (by evoking earth element into the water
and transforming it to make it a hard surface over the spot where the
ruesi is currently standing).
in the same way, one could also dive under the earth too, or float
in the air, transport oneself instantly from one place to the other for
example.
This is probably what the ancient Alchemists (such as saint Germain) of the mediaeval Era were attempting to do.
other abilities acheived include divine ears and eyes (ability to see
and hear things in other spheres/dimensions), read minds, and tell the
future.
Por Gae a Buddhist?
Because of the evidence pointing to the Ruesi Por Gae Tha Fai having played an important role in the creation of the "Pra Sum Gor Amulet, it is evident that Por Gae respected the Buddhist faith.
he can be supposed to have been an extremely important figure in the land because the Pra Sum Gor statue and amulets were made in what is believed to have been a rather large cermony, probably a royal Ceremony because the filigrain detail of the statue and amulets indicate a major event.
Por Gae is also known as Ruesi Isworn (ishwara), because it is considered that Ruesi tha Fai is an incarnation of the Divinity Shiva/Isworn - the third eye is a symbol thereof.

One of the most well heard of Ruesi in Thailand's pantheon of Ruesi figures is that of
Por Gae Ruesi Tha Fai (พ่อแก่ฤษีตาไฟ)
Por Gae Ruesi Thai Fai appears in numerous legends and Myths as well as historical documents.
For
example in the history of the arisal of the Province of Petchaburn,
there is a famous story that tells that the King/Rulerof petchaburn in
that time had learned Sorcery with Ruesi Tha Fai.
But after he recieved the teachings and knowledge, he planned to kill his own master Por Gae Ruesi Thai fai!
As a result Por Gae Ruesi
cast a curse on the Province of Petchaburn, and a great plague resulted
in leaving the whole province almost void of living inhabitants.
Another occurence of Por Gae Ruesi Tha fai in Thai legends is that of the creation of the Pra Ta Gradan amulet;
This amulet is from Wat ta Gradan (on of the three main temples in
kanjanaburi province on the banks of the river Kwae (or Kwai as farang
tend to call it - to the great amusement of Thais).
Pra ta Gradan amulets are inclined to have red eyes (suggesting fire
eyes as is the meaning of "Thai fai" (Tha fai means fire eye/s).The
facial traits of many examples of Pra ta gradan are also very similar
to the facial aspects of Ruesi.
Apart from this, Por Gae Tha fai
is also reputed to have had a part in the creation of the Pra Sum Gor
Amulet; The legend tells that fwhen this amulet was in the making,
there were four different Ruesi presiding over it's creation.
Namely;Pra Ruesi Pilaalay (พระฤษีพิลาไลย) Pra Ruesi Tha Fai
(พระฤษีตาไฟ), Pra Ruesi Narod (พระฤษีนารอท), and Pra RuesiGaiyagost
(พระฤษีไกยโกษฐ์).
This Amulet is counted as one of thge five "Pra Benjapakee"
amulets wich are reputed to have an age of not less than one thousand
years.
because of the documented evidence appearing in various historical
recordings related to the creation of these amulets, and the fact that
all of the aforementioned amulets date back to more that one thousand
years ago, it can be assumed that Por gae Ruesi tha fai really existed,
and that he lived at least one thousand years ago, if not more than
that.
Because of the ability of Ruesi to live for hundreds of years, it
cannot be known how far back his appearances go... M y master Ajarn
Thoy, who is a medium for the presence of Por Gae ruesi tha fai, says
that Por Gae was around two thousand years ago - meaning that this
Ruesi may have been able to extend his lifespan for up to one thousand
years, if the accounts relating to the creation of the aforementioned
amulets are true.
This extreme extension of lifespan is also accredited to the great
alchemist St. germain, who in principle learned the very sam methods of
elemental transformation and evocation as the Ruesi.
In principle the Ruesi were also alchemists, becasue of their ability
to transform one element into another.