Requesting and killing the prisoners didn't involve much deceit.
Based on what he knew, the deceit involved in this was Lieutenant Rafi telling his men to lie to the prisoners that they would be freed to make the transportation process smooth. Lucivar has no mix with that small deceit.
His involvement was indirect.
Naturally, Loki rewarded him with only a pebble of green spheres from each of the prisoner's death.
Hundreds of pebbles that probably wouldn't amount to the green sphere he obtained from his very first kill in that stable, it was that minuscule. However, with his performance—fooling the crowd that he was forced to kill the prisoners in order to ensure their safety, the prisoners' deaths were now touched by his deceit.
All of their deaths became exponentially more important than mere rewards from the city.
Instead of mere rewards, the dead prisoners became the necessary sacrifice to ensure the city's survival.