No, it would not be feasible to base jump off Deimos or Phobos to land on Mars. Deimos and Phobos are the two moons of Mars, and their relatively small sizes and weak gravitational fields make such an endeavor impractical and dangerous for several reasons:
Gravitational pull: Deimos and Phobos have significantly weaker gravitational fields compared to Mars. The surface gravity on Mars is about 38% of that on Earth, whereas the surface gravity on Phobos is about 0.005% and on Deimos is about 0.003% of Earth's gravity. The low gravity of the moons would not provide enough acceleration or velocity for a base jump to propel you to Mars.
Orbital velocities: Both Deimos and Phobos are in relatively close orbits around Mars. Their orbital velocities are much lower than the escape velocity required to leave their respective orbits. Even if you were able to jump off one of these moons, you would still be in orbit around Mars rather than landing on the planet.
Atmospheric entry: Even if you managed to leave the moon's surface and enter Mars' orbit, entering the Martian atmosphere without proper equipment and protection would be extremely dangerous. The high speeds during atmospheric entry would generate intense heat and forces that would pose a significant risk to human life.
In summary, base jumping off Deimos or Phobos to land on Mars is not a feasible or safe method of reaching the planet. Space travel to Mars requires sophisticated spacecraft and careful planning to ensure the safety and success of the mission.