Here's a video describing all three achievements. Lunar Eclipse achievement is described last in the video. Basically, you must spell out Moon Knight by completing each mode of the game.
M - Defeat Morpheus via the mission ramp
O - Defeat Bushman via the mission ramp
O - Defeat the Black Spectre via the mission ramp
N - Defeat Nightmare via the mission ramp
K - Complete Taxi mode
N - Wall Street mode, once activated simply hit the middle hole to finish it.
I - Crossbow mini game, clear stage 1
G - Rough Customer mini game, clear stage 1
H - Nightmare multiball, simply activate it
T - Moon Copter multiball, simply activate it
Once you spell out Moon Knight, you hit the Mission Ramp one more time to begin the final stage to defeat Seth. You need to hit the left and right ramps, twice each and the middle hole 4 times in under about 60 seconds. And after that, there's a final multiball phase where you must score *50* orbs by hitting various ramps and orbits. Each hit yields an orb or two. It displays your progress to 50.
If you fail the final stage, you simply need to hit the Mission Ramp again to activate another try at the final stage.