The Legend of Sol, Titan, and Morgan: A Request

Sol and her siblings were welcomed graciously into the castle: that alone was enough to make Sol suspicious about what the Baron wanted. Neither Titan or Morgan were impressed, but neither also seemed to be very interested in what all of the welcoming and hubbub could mean: rather, they seemed most concerned with leaving the castle, and returning to the lives that they had begun to live in Canterlot.
The Baron was waiting for them in the same hall where they had spoken before, safe on his high perch, with his mages standing at the ready by his side. Sol could feel the magic they had prepared, but she also sensed that there was no hostility towards them. Instead, the Baron looked desperate: he was clearly very much afraid of something.
Sol wasted little time on pleasantries, asking him politely but clearly what he wanted from them: the Baron was slow to respond at first, and while his hesitance irritated Morgan and left Titan looking bored, Sol focused on it. She could not imagine what would make the Baron so nervous.
Finally, he spoke to them, and to Sol's pleasant surprise, he chose to speak plainly. He told them that for the last year, he had been paying a secret tribute to a cruel tyrant who had come to these lands, and was choking the roads with her skeletal soldiers. He had been paying her great sums in wealth and accumulated knowledge each and every week, so that she would keep the highways through the barony clear of her mercenaries and monsters, but she had begun to ask for more and more.
She had asked for bodies to be sent to her: the Baron had complied with this request with little hesitation, for there was rarely a shortage of corpses in these wild lands. Then she had asked for living subjects, but the price had been cheap: only three at first. So he had sent her three prisoners who had been awaiting execution.
But the next week, she had asked for five, and the week after that, six. Soon, she was requesting a dozen living subjects to be sent to her, and the Baron had too few undesirables locked up in the dungeon. He had sent them all anyway, with a gift of treasure... and none of his couriers or soldiers had come back alive, and the attacks on the roads had resumed, making it impossible to travel through the barony once darkness fell.
Then, a few days ago, a message had arrived, warning him that a payment of no less than twenty living subjects was expected to be sent as payment, or a great army of the dead would march on Canterlot. The Baron was terrified, and had no one else to turn to.
Morgan and Titan were both quick to volunteer their aid, but Sol fell deep in thought. The Baron waited fearfully for her answer, but it was slow to come. And when she spoke, it was not what the Baron expected:
"Prepare twenty ponies to be sacrificed. We shall take them to this Lich ourselves."