An integral criterion of ignition in the inhomogeneous plasma of a toroidal reactor is obtained. The possibility of using this criterion for burn control in a reactor operating near ignition with a high energy gain is demonstrated by means of numerical modeling. The existence of an ignition scenario with decreasing temperature before ignition is demonstrated and explained. It is shown that a temperature profile near the unstable steady-state profile can be achieved by the appropriate choice of auxiliary heating characteristics. A method of continuous operation, based on weak modulation of the heating power, is proposed.