A resonator based on a positive branch confocal unstable resonator with toroidal curvature mirrors is presented. The mirrors have different radii of curvature in perpendicular directions. In one direction, the curvature (main curvature) is strong, and it governs the main properties of the resonator. In the perpendicular direction, there is a weaker (secondary) curvature acting to decrease resonator's sensitivity to mirror tilts. Resonators of different size, gain, and output coupling are examined, and attention is given to phase distributions, near-field intensity, beam quality, and intensity distribution. Focus is placed on basic eigenmodes for uniform and nonuniform gains, mirror tilt, and phase perturbations. High far-field intensity and increased power-extraction efficiency in nonuniform active media in such a resonator are emphasized.