Bodhichitta and Emptiness are the best purifiers.
Neither are very specific so generate Bodhichitta and practice Vajrasattva. Or the Three Heaps Sutra with them.
For full purification, you need the Four Powers: Regret, the Purification practice itself, Turning Away from the Fault, and Reliance on the Three Jewels. Phabongkha Rinpoche said that all four are explicitly in the Three Heaps Sutra.
Equanimity is the ground. Love is the moisture. Compassion is the seed. Bodhicitta is the result.
-Paraphrase of Khensur Rinpoche Lobsang Tsephel citing the Guhyasamaja Tantra
"All memories and thoughts are the union of emptiness and knowing, the Mind.
Without attachment, self-liberating, like a snake in a knot.
Through the qualities of meditating in that way,
Mental obscurations are purified and the dharmakaya is attained."
-Ra Lotsawa, All-pervading Melodious Drumbeats