Trapped {Boyxboy, Drarry Fanfiction}

In this Drarry Fanfic, there are no such things as Horcruxes and the only way to kill Lord Voldemort is to use a powerful spell that only Dumbledore knew. Now Harrpy Potter must somehow find out about this spell, and needs Draco Malfoy's help. There is also a strange Prophecy hanging over his head:

When the Chosen One unleashes his power,
The Dark Lord will be vanquished,
But it will also bring a terrible ruin,
And trap him in an eternity of darkness.