As you hold up the focus of the spell, it starts to glow with arcane energy and emit a high-pitch sound. At any given time you may, as an Action, release the energy that the linse holds, into a ray of power, dealing 6d8 force damage to a creature hit. At the end of each of your turns, if you have not activated the linse, the damage of the ray increases with 1d8 to a maximum of 10d8. 

Once the linse has been activated, the spell ends.

at higher levels: When cast at a higher level, the initial damage increases with 1d8 and the maximum damage with 1d8