The end is nigh. The party devides, new people join the fray. Grimm and 3 others, a bard with a song on his lips, a paladin with a journey to take, a ranger with a sword in his hand.
They were seen to the barrier and then they leaped in side

I followed them into the city of darkness and fire. It is the end of the world. The Gods themselves for their survival. But there is hope; in the breast of these men and women, wherein lies the salvation of the universe.
Grimm’s eyes have no hope in them. Only darkness. Only silence.

They flew over rooftops, traveling as fast they could to reach the heart of the darkness, the seat of despair: the temple complex where Rovagugkun was quickly finishing his last touches to let his master through.

They arrived with little trouble til they tried to enter the temple itself. Then they encountered two twins of smoke and flame. Grimm took his chance and in the confusion and violence and shadows left them behind entering the temple ahead of them.
This is the beginning, his betrayal, the end of all hope.
He talks quickly to Rovagugkun, and agrees to keep the others here where they can not interfere with the ceremony.
I will need to defy my orders, kill the betrayer or all hope is loss, but wait…

the rest of the party enters the temple.
His tongue is like a serpent, spreading easy and luxury and peace. Even I begin to doubt, maybe it is better to just have it end.
No more pain, no more suffering, no more war, no more hate.
Peace forever
The ranger attacks, his desire to live and naivety and the optimistic hope for a better world is greater than his reason.
It’s a poor swing, clearing missing.
Grimm raises the crossbow, aiming at the ranger’s chest, ready to put one more soul out of his misery, and grimm moves in front of the swing of his sword, lifting his arm so that is in its path.
And his arm is gone. Abandoned as easily as if it had been a lock of hair, and Rovagug can no longer tell his actions or his purposes or his plans.
I can See into his heart now though, and it is dark indeed. But his purposes remain the same, his road as obvious as it always was, his path as straight. There was no room for good in his heart. Because it was filled with his intent, his obsession. The destruction of evil, even if it stained his own soul, made him as dark as them, because he knew he too would die one day. And he would relish that day because one more evil creature would be gone.
But till then he would slay one at a time. And he would not pass up the chance to destroy the most evil thing that had ever been.

He descended into the deeps, for one last fight.
Now Rovagug and Rovagugkun would not see his betrayal coming.