Dominic de Guzman believed the best way to attack heresy was?

In the beginning, to attack it head on with truth, logic and the Gospel. But St. Dominic continued to pray furiously for their conversion. After many years of this, he saw an apparition of our Blessed Mother and she gave him a rosary and told him God had granted special graces to the praying of the rosary and meditating on the mysteries of our redemption revealed in Christ's life on earth. She told him to pray rosaries for their conversion. He did this and the heretics who were previously hardened, began to see the truth of the Gospel and the number of conversions were miraculous.