You create a magically shield around a large area of a 300ft radius. Damaging magical spells, siege attacks and other elemental damage can not pass through the shield. Creatures can pass in and out of the of the shield at will. It can extend above ground in a dome or in a sphere below ground as well at a cost of 150ft of radius.
If more than one caster casts this spell then the spells radius increases by an additional 300ft. So three spell casters would be able to create a 900ft radius magical dome shield.
