You may have heard or read in books about the predictions that Guru Shakyamuni Buddha made about Lama Tsongkhapa, so I will not mention them here. Without doubt Lama Tsongkhapa is the one father of all the Victorious Ones, which means Manjushri. That is proven by logic and by stories about him. Strong, definite faith comes from hearing those many quotations in regard to him, principally from Guru Shakyamuni Buddha. In the Manjushri Root Text Buddha says, "After I have passed away, you will in the form of a child perform the actions of buddha." Also Guru Shakyamuni Buddha said, "At that time a monastery called "Extremely Joyful" will be founded", which refers to Gaden Monastery. Also in the scripture Kadam Lekpam Guru Shakyamuni Buddha said, "One of my transformations will be as a bhikkshu." Also Padmasambhava said, "A manifestation of Manjushri, the holder of the teachings, who will reveal the teaching to those who are to be subdued, Losang Dragpa, holder of the sutra and tantra teachings, will appear." So, there are many reliable quotations and logical reasonings to establish who Lama Tsongkhapa was.
All the buddhas of the ten directions abiding in the infinite pure fields say, "Lama Tsongkhapa is a very brave-hearted bodhisattva, the holy being who clarified the teachings of Nagarjuna and Asanga, the great propagators of the profound and extensive teachings of Buddha." Hence (the epithet) "Tsongkhapa, the Dharma King of the three realms, Losang Dragpa". Dechen Phabongkha says: "If one keeps even a drop of the nectar of the name of this holy being Lama Tsongkhapa in a devotional heart, it plants the seed of liberation and one receives the fortune to practice and enjoy happiness from this life up to enlightenment." I think this refers particularly to ultimate happiness.
In my opinion to have the opportunity to practice this great holy being's yoga is, in general, even more fortunate than having the opportunity to receive other teachings and the opportunity to do other dharma practice. Attempting the guru yoga practice of the inseparability of your own root guru and Lama Tsongkhapa establishes the root of all happiness from this life up to enlightenment. Attempting this guru yoga practice is that which causes all the teachings that you listen to and reflect on and meditate on to go to the right point. Go to the right point means to be of benefit. Every single teaching taught by Buddha — sutra and tantra — is only for the purpose of subduing your own mind. That is the only purpose. So, whatever you do — listening, reflecting, meditating, everything — is for subduing your own mind. This guru yoga practice does that. Its purpose is to direct your mind so that listening is not outer listening, reflection is not outer reflection, meditation is not outer meditation — rather that they are inner practices and thus subdue your mind.
If you do the Lama Tsongkhapa guru yoga practice and train in the lam-rim by listening, reflecting, and meditating you will not be attacked by obstacles. Regarding obstacles there are three types. In the commentary on Jorchoe it explains that one should make requests with the three purposes at the end of the mandala offering. In that prayer it mentions the outer and inner obstacles, which includes all the obstacles. In the commentary it also mentions outer, inner and secret obstacles. Inner obstacles are the delusions. Outer obstacles are harms from other living beings and even non-living things such as the elements — which are caused by one's own delusions and karma — which do not allow one to continue practicing the holy dharma. Things such as diseases are outer obstacles. In one of the commentaries it says that secret obstacles are being under the control of somebody who is either an evil-doer or wrong guide, such as a king or some other being, and not having the opportunity to practice lam-rim. However, if you do the Lama Tsongkhapa guru yoga practice you will not get attacked by these outer, inner and secret obstacles.
You will also be protected from harms such as paralysis due to trib (pollutions). This pollution is not necessarily like factory pollution. I think if there is no inner pollution then outer pollution cannot harm one. Degenerating samaya vows taken during initiations and things like that are the heaviest pollutions and paralysis comes from those. By degenerating the samaya of the holy body one gets leprosy disease and many physical problems. By breaking the samaya of the holy speech one becomes mute, dumb and things like that. By degenerating the samaya of the holy mind the mind becomes crazy or very disturbed and things like that. However, by doing the Lama Tsongkhapa guru yoga practice one gets protected from the inner and outer pollutions.
While you are doing guru yoga practice you are not doing the opposite of guru yoga. If you do your various practices with the understanding of guru yoga the results will come effortlessly. It all depends on how strong the guru yoga is in your mind. Much fewer difficulties will arise in your practices and therefore you will not break samaya, and so will not create new causes of problems. Also, you will purify the vices or the negative karmas that have been accumulated in the past. So, in this way there will be no inner pollution and no harm from outer pollution. The spirits called gyaelpo (king), and naga kings, and powerful spirits situated in certain rocky places, called tsaen, and the three hundred and sixty spirits called doen will not be able to give harm. So, by practicing guru yoga you will be protected from those harms.
Also, you will be able to accomplish exactly what you wish. The specific benefits of the Lama Tsongkhapa guru yoga practice are gaining great, quick and profound wisdoms. Phabongkha Dechen Nyingpo said: "If one does the recitation of the Lama Tsongkhapa guru yoga prayer for even one month using one of the visualizations for great or clear or quick wisdom, one will definitely see development of that wisdom. It is proved by experience. There is no doubt that by doing the Lama Tsongkhapa guru yoga practice one can meet Lama Tsongkhapa's teachings from life to life. And furthermore, it gives one the opportunity to be born in the pure realm of Lama Tsongkhapa, Tushita, whenever death happens." So, there are infinite benefits from practicing Lama Tsongkhapa guru yoga.
It is commonly known that when people have much lung (wind disease) it can be cured by doing migtsema practice, perhaps in a retreat, using a particular visualization. There are various things to do in connection with migtsema to give protection from the dangers of weapons and to cure paralysis; also to stop rain or make rain, and to give protection from that which causes people to become crazy. So, there are various things you can do to be able to continue your dharma practice as well as to benefit other sentient beings.
In Tibet one great lama, Sherab Sengye, and his disciple Dulnagpa were meditating in a mountain valley called Se. In that valley there was a very wealthy family and the son was possessed by a type of spirit called gyalpo. They tried various means but nothing stopped the possession. One day the shepherd who looked after this family's animals told them, "Sometimes I see a big yak on the mountain and sometimes a monk." So they went to check the hermitage. They requested the lama there to come down and do something for their son. At first this lama did not accept. Again they insisted. So then the lama checked and saw it was time to subdue the mind of this sentient being and so he said, "I will check whether I can be of benefit or not; if I can benefit then I will come down. First take my shoes and one bead from my mala. Hang the shoes from the ceiling over where the son sits and leave the bead at the window. Then check what the son says." So they did that and the spirit king screamed because he had the appearance of a great mountain pressing down on him and the bead that lama had given appeared to him like there were terrifying wrathful deities around him. The spirit was screaming, "Now where should I stay?" So the family went to see the lama and explained this and so the lama realized that now he could control the spirit and benefit the son. So he came down and put the spirit under pledge. In front of that lama the spirit king promised to not give harm wherever migtsema is recited. Then the lama said, "If you don't keep this vow I will smash you into atoms immediately!" And the spirit king said, "You are a bodhisattva, so please have compassion for me: there are not so many places where migtsema is not being recited, so where should I go?" — he was only referring to Tibet, I think. I think the lama said to go to Italy! I'm joking! So, one of the particular benefits of migtsema practice is that this spirit promised to not harm whoever does this practice. The harm sometimes takes the form of sudden fainting or sometimes the eyes roll up and the person shakes. The way the person gets sick may not always be the same. So, Lama Tsongkhapa guru yoga practice is regarded as a great puja for the success of one's own dharma practice, as well as for others.
A method such as this guru yoga based on the inseparability of Lama Tsongkhapa and your own guru, the lama, establishes the very root of all happiness, for all the good things, from this life up to enlightenment. It makes whatever you do — listening, reflection and meditation practice — become effective for your mind. It makes whatever you do become dharma: your mind to become dharma, and dharma to become the path, and for no obstacles to generating the path to occur. "The mind to become dharma" includes the whole of the graduated path of the lower capability being, from the realization of the perfect human rebirth up to karma. With these realizations, with this awareness the mind becomes dharma. Then, with renunciation of the whole of samsara the dharma that you practice — the listening, reflecting, and meditating — becomes the cause of liberation; so "dharma to become the path" includes the graduated path of the medium capability being. As the main obstacle to the path is the self-cherishing thought, "for no obstacles to generating the path to occur " means to have bodhicitta. With bodhicitta, whatever listening, reflection and meditation practice you do becomes the cause of enlightenment. As bodhicitta is the door of the mahayana path, through that you are able to complete the mahayana path and achieve the state of omniscient mind. So, "for no obstacles to generating the path to occur" includes the entire mahayana path.
If you practice this guru yoga you will not experience inner or outer obstacles. You will be protected from harms such as pollutions, paralysis, and the different types of spirits — nagas, king, or tsen. All of your wishes will be fulfilled, and in particular you will achieve the great, clear, quick, and profound wisdoms, and the wisdoms of explanation, composition and debating. Also, without doubt you will be able to meet Lama Tsongkhapa's teaching life after life. Also, by doing Lama Tsongkhapa guru yoga, when death comes you will be able to be reborn in Tushita, the pure realm of Lama Tsongkhapa.