The build is based around the new staff and lightning damage.
Grinding Gear Games has shown a user build under the nickname Shadow Edwin in Path of Exile 2, turning the mage into a real combat unit capable of dealing several million damage to bosses in a matter of seconds.
The build is based around the "Unborn Lich" staff and its passive property, giving 20 points to the "His Sweeping Disaster" charms, and the Titan class was taken as the basis.
How exactly Shadow Edwin turned the Titan into a combat mage can be seen in the video below