Both Heart Jewel and Wishfulfilling Jewel are Guru yogas of Je Tsongkhapa combined with the sadhana of his Dharma Protector. This sadhana (a formal practice consisting of prayers, visualizations and meditations on a specific Deity) includes two practices revealed by the Wisdom Buddha Manjushri. The first is a special Guru yoga in which we visualise our Spiritual Guide as Je Tsongkhapa, who himself is a manifestation of Manjushri. By relying upon this practice, we can purify negativity, accumulate merit, and receive blessings. In this way, we shall naturally accomplish all the realisations of the stages of the path of Sutra and Tantra, and in particular we shall attain a very special Dharma wisdom.
The second practice is a method for relying upon the Dharma Protector Dorje Shugden. Through this, we can overcome obstacles to our practice and create favourable conditions so that we can nurture and increase our Dharma realisations. If we rely upon the Dharma Protector Dorje Shugden sincerely, our faith in Je Tsongkhapa will naturally increase and we shall easily gain experience of the pure Buddhadharma transmitted directly to Je Tsongkhapa by the Wisdom Buddha Manjushri.
These two practices are the very essence of the New Kadampa Tradition of Mahayana Buddhism. If we practise them regularly and sincerely, we shall reap a rich harvest of pure Dharma realisations, and eventually come to experience the supreme joy of full enlightenment. An extensive explanation of this sadhana can be found in the book Heart Jewel, by Geshe Kelsang Gyatso available from Tharpa Publications.

The chanted prayer we do regularly in Dharmavajra Centre is called Liberation from Sorrow and consists of praises and requests to the Twenty-one Taras.  Tara is a female Buddha, a manifestation of the ultimate wisdom of all the Buddhas. Each of the Twenty-one Taras is a manifestation of the principal Tara, Green Tara. Tara is also known as the `Mother of the Conquerors’.
Tara is our common mother, our Holy Mother. When we are young we turn to our worldly mother for help. She protects us from immediate dangers, provides us with all our temporal needs, and guides and encourages us in our learning and personal development. In the same way, during our spiritual growth we need to turn to our Holy Mother, Tara, for refuge. She protects us from all internal and external dangers, she provides us with all the necessary conditions for our spiritual training, and she guides us and inspires us with her blessings as we progress along the spiritual path.
Tara means ‘Rescuer’. She is so called because she rescues us from the eight outer fears (the fears of lions, elephants, fire, snakes, thieves, water, bondage, and evil spirits), and from the eight inner fears (the fears of pride, ignorance, anger, jealousy, wrong views, attachment, miserliness, and deluded doubts). Temporarily Tara saves us from the dangers of rebirth in the three lower realms, and ultimately she saves us from the dangers of samsara and solitary peace.
If we rely upon Mother Tara sincerely and with strong faith she will protect us from all obstacles and fulfil all our wishes. Since she is a wisdom Buddha, and since she is a manifestation of the completely purified wind element, Tara is able to help us very quickly. If we recite the twenty-one verses of praise we shall receive inconceivable benefits. These praises are very powerful because they are Sutra, the actual words of Buddha. It is good to recite them as often as we can.

Offering to the Spiritual Guide is a special Guru yoga of Je Tsongkhapa in conjunction with Highest Yoga Tantra. It was compiled by the first Panchen Lama, Losang Chökyi Gyaltsän, as a preliminary practice for Vajrayana Mahamudra. The main practice is relying upon the Spiritual Guide, but it also includes all the essential practices of the stages of the path (Lamrim) and training the mind (Lojong), as well as both the generation stage and completion stage of Highest Yoga Tantra.
The essence of Guru yoga is to develop a strong conviction that our Spiritual Guide is a Buddha, to make prostrations, offerings, and sincere requests to him or her, and then to receive his or her profound blessings. According to the Guru yoga of Offering to the Spiritual Guide, we develop conviction that our Spiritual Guide is the same nature as Je Tsongkhapa, who is an emanation of the Wisdom Buddha Manjushri.
By relying upon Je Tsongkhapa, our compassion, wisdom, and spiritual power naturally increase. In particular, because Je Tsongkhapa is an emanation of the Wisdom Buddha Manjushri, his faithful followers never experience difficulty in increasing their wisdom. There are many other benefits from practising Offering to the Spiritual Guide. These are explained in the book Great Treasury of Merit, which contains a complete commentary to the practice.