A few more shots:
"An apostate nun determined to save lives. A grieving father obsessed with revenge. Together they'll lead a peasant insurgency against warlords on both sides of a brutal dynastic struggle, and uncover the dark foreign conspiracy behind the bloodshed."
Or slightly alternative,
"She's determined to save lives. He's obsessed with revenge. Together they'll lead peasant insurgents against warlords and monarchs on both sides of a brutal dynastic struggle, and uncover the dark foreign conspiracy behind the bloodshed."
Or
"Alessia left the temple cloister to save lives. But when the peasants that follow her launch vengeful terrorist attacks against both sides of a brutal civil war, she'll risk the lives she's saved in a bid to bring it to an end."
Or
"Robin Hood's Merry Men meets the Fremen from Dune when fed-up peasants launch a "pox on both your houses" insurgency against both sides of a bloody civil war, led by an exiled nun and revenge-obsessed farmer."
Or
"Lowborn peasant guerrillas throw a wrench in a scheme by a foreign bank to prolong a bloody civil war when an exiled nun and a farmer obsessed with revenge join forces."
Or
Apostate (or: Disillusioned?) nun quits the cloister to heal wounded in a brutal dynastic war. She unwittingly finds herself leading vengeful peasant insurgents against both sides, risking those she's saved to expose the foreign conspiracy funding the bloodshed and bring it to an end.