Not gonna lie, I suck at rhyming from scratch, but can re-write existing lyrics well enough to have a decent end result. Why? For fun of course.
So... in order to combat the total death of this group due to total inactivity of our respected members, I post something I made as a little thing while working on my story. It's vague enough not to spoil anything major,

From the heart of the darkest sea
They attacked the home of ponies and humanity
The City of Canterlot was in danger.

There's a foe worse than a thousand swords
Shining metal obedient to their dark lords
Their fall from grace will pave their path, to damnation

Then the 129
In the service of heaven
They're protecting the southern line
It was 1089. Gave their lives to fight the Descendant swine.
Thy will be done!

For the grace, for the might of our sun queen
For the home of the holy
For faith, for victory the keen
Rangers gave their lives so boldly

For the grace, for the might of our moon queen
For the tale of their glory
For faith, for victory of the keen
Come and tell their story again.

Emboldened by the forgiven mare
Strengthened by her care
The King of Willpower was rising.

Striking at the terror of the sea
He brings them deadly Trinity
His path trough history is paved with annihilation.

Avenging the 129
In the service of heaven
Those protecting the southern line
It was 1089. Gave their lives to fight the Descendant swine.
Thy will be done!

For the grace, for the might of our sun queen
For the home of the holy
For faith, for victory the keen
Rangers gave their lives so boldly

For the grace, for the might of our moon queen
For the tale of their glory
For faith, for victory of the keen
Come and tell their story again.

Dying for salvation with dedication
No capitulation, annihilation
Royal commendation, reincarnation
History is your destination

In our rulers name!

For the grace, for the might of our sun queen
For the home of the holy
For faith, for victory the keen
Rangers gave their lives so boldly

For the grace, for the might of our moon queen
For the tale of their glory
For faith, for victory of the keen
Come and tell their story

Gave their lives so boldly
Come and tell the Harmony Rangers' story again.

In short, sacrifices were made, but we already had that with the attack of the void beings, so it won't mean the end. Have fun speculating what might happen in the future.