Not quite about slaying a dragon, but better.

Three Dragons

Upon a lonely mountain
Where the wind blew dark and cold
Sat a silver dragon
In a lair lined with gold

Far away at the ocean
With waves sharp and steep
A shadowed winged creature
Emerged from the deep

And when it broke the surface
Thunder and lightning in the sky
A third and final dragon
In the desert heard its cry

Three dragons in the sky
Three dragons flying high
In a world crushed by Lord Destructor
With no forces to save the stars, and the planets, and the galaxies
Three heroes take flight
Three heroes to the fight
In the night, in the night, in the night
Three dragons

Upon a steel-plated airship
Lord Destructor sat enthroned
He ruled over the cosmos
A universe he called his own

And his minions arrived in thousands
Bearing gifts of blood
Their king had a hunger
For baby animals filled with love

It didn't matter where they came from
It didn't matter what they said
Lord Destructor was merciless
On their little souls he fed

[And then – from behind the stars!]

Three dragons in the sky
Three dragons flying high
Their talons ripe for battle
Fierce hearts armed to save the stars, and the planets, and the baby animals
Lord Destructor shot out his beam of malevolence
But the dragons met it with an eruption of fire
Swarming him and striking with furor
Their righteous power breached his armor
So that the baby animals could climb inside and tickle him
To death! To death!
Lord Destructor is dead, he's dead, he's dead, he's dead
The dragons have won – let the baby animals frolic in the universe!
Let them frolic!
Be free!
Fly!