Sädekivi
The Sädekivi (listen 
) (also known as Beamstone), is an inventory item. It can be obtained by collecting the Summon Sädekivi perk.
Usage
If you kick the item while it's on the ground (or try pulling it with Telekinetic Kick perk), it will vanish, and a beam of light will appear in its place. Along with it, a message: You feel like you should move...
This beam will charge up for a few seconds, before exploding, dealing 125 ♥ projectile damage per frame (up to 500 ♥) to any creature unfortunate enough to be inside. Additionally, all solids above the beam, even unloaded ones, will be removed in a wavy pattern.
If any spells within Holy Mountain shops are in the range of the beam, they will drop down to the point of origin, including spells with a price tag on them (this will also make them free).
It makes for a great tool to get back to the surface.