Keristrasza wants you to use the Power Focus to lure Saragosa, and then defeat her.
Using the mana crystals you provided, I have created this Power Focus.
Saragosa is a glutton. She will be unable to resist its lure. Inside it lie magics that will greatly diminish her power. Let us hope she does not see through my ruse....
Prepare yourself, <name>, and speak to me again when you are ready to face Saragosa.