Show me the magic!

[Drakenbow]

Originally Posted by hcobb

"Created wall is a manifestation of the magical principle of immovability. It does not have any actual potential energy to harvest. If moved or toppled it vanishes instead."
https://www.hcobb.com/tft/house_rules.html#iq11spells

Is this from the book or a House Rule? I mean fantastic if a wizard could create a one-hex wide / 3-hex tall stone bridge hanging in the air.