How to Defeat the Master in Strider

Strider (Called Strider Hiryu in the land of atomic lizards) is an action arcade video game designed by Capcom in 1989. The game's protagonist, Strider Hiryu, runs fast and performs quick striking maneuvers as he's frees his the world from the Master, the evil warlord who is also known as the Grandmaster, who rules over it. Strider fights the Master who is the final boss located at the end of Stage 5. To get to the Master, you must defeat Lago. Once he is defeated, you can finally ride to the Master's domain and free the world of the Master and his evil schemes.

Step 1
Press the "A" button to attack Lago when he is extending his claw or jumping. Do this until he falls down.

Step 2
Press the "B" button to jump on top of the uroboros creature that appears after knocking Lagos down. Ride the creature for a few minutes. Soon, you will hear the Master's voice. Right after you do, the creature will enter the Master's domain.

Step 3
Strike the uroboros in the head until it starts blinking by pressing the "A" button. Move as close as you can to the front of the creature. You will fall off the beast.

Step 4
Obtain the full health bar by jumping (the "B" button) at the health pack at the top right of the screen. Obtain the sword powerup at the top left of the screen by jumping at the sword pack.

Step 5
Dodge the lightning bolts the Master throws at you by running back and forth. Attack the monsters that come from the lightning bolts with the "A" button. Jump with "B" and attack the Master in between his lightning bolt strikes to destroy him.

Source: GameFAQs: Strider FAQ/Walkthrough