The Problem At The Mets Game...

Lily and her friends walked to Hades palace. Drew had managed to charmspeak the guard into letting them down. When they got to the palace, Lily addressed The Lord of the Dead.
"Lord Hades!" She cried. "I have an offer for you. The reign of the Olympians has gone on for far to long. With our help, you could overthrow them. We could start a new Golden Age; one where you and the rest of us rule the world."
Hades pondered this for a moment.
"I like it." He said. "What do you have in mind?"
"Well, my lord, how do you kill a god?" Lily asked.
"You can't- they're immortal."
"Exactly. So first, we've got to turn the Olympians mortal. Cody can make a potion that will turn an immortal being mortal. Then, we can sneak into camp and burn them as sacrifices. The potion will be cleverly hidden in regular food items, so that the gods won't suspect a thing. Then, when they are mortal, we will strike."
Everyone was silent. No one had anticipated a plan this well thought out.
Suddenly, Hades started to clap.
"You're a genius." He said. "What's your name?"
"Lily." Said Lily. "Lily Collins."
"Well then, Lily Collins, are you ready to start a war?"
"Oh, Lord Hades." Lily smiled, sweetly. "The war has already begun."
Lily then started to go through the rest of her plan with Hades.
"I need you to get Arachne out of Tartarus." She said. "I need her as an alli. And, while you're down there, get the giants and the Titans. And any other monster you think would be useful. Empusai, drakons, demons, anything. I need a bigger army."
Hades said, "I will do this. But, have you considered going to the Romans? They are skilled fighters, and you could probably convince some of them to join you."
"I'm in contact with some Romans." Gabby said. "Some of them have some hatred for the gods. They will be useful."
Lily nodded.
"Drew and Gabby, you will go to Camp Jupiter and recruit some demigods. Cody, start working on the potion. Will, you and I will work on a battle strategy. We attack Camp Half-Blood in a week. And Lord Hades, release the worst monsters in Tartarus, and bring them to me. Especially Arachne. I have a deal to make with her."
Everyone nodded and grinned evil grins.
"Right." Said Hades. "Let's get to work."

Notes

How does Lily plan to get Arachne on her side? And what deal does she have in mind?