Blue triumphant

No one was surprised when the war came.

What was surprising though, was the outcome.

The devil was more powerful and his army was larger in size.

Unfortunately his troops were neither as well trained or as loyal as he was used to, as a prince of hell.

His human armies deserted at the first opportunity.

Zartak was forced further and further back into the northern territories until he was finally cornered.

Thereanthor had come personally to lead her dragon-borns and Black cloaks.
Thousands of Dragon-borns had been unwittingly pulled back through to Fissa at the time of the portal rend.

They were loyal to her and grateful as she protected them from harm even as they threw themselves blindly forward.
Thereanthor had a secret weapon though.
A group of troops that she'd kept secret until that moment.
Tieflings.
Thousands of them.
Zartak had been unaware of his own contribution to his own destruction.
When he breached his section of the planar barrier, years before, the tormented legions of half human, half devils had been released into this world.
Despite their heritage, they hated all pure-blood devils.
A hatred they directed at Zartak.

Tens of thousands died in that last battle but it was the dragon herself who ended it.

Her jaws closed around the giant devil’s throat.

Her entire weight upon his.

Zartak wasn’t killed though.

You can’t kill an immortal.

His massive body crumbled into chalk-like pieces and his essence was pulled back to the pits of his fiery prison.

As his body coalesced, his screams of vengeance shook the gates of hell.