Moving will be made to interrupt spellcasting at a point in time...

[Fey]

You need to focus the image in your head. This is why a lot of fiction shows casters closing their eyes. They use rods to focus their spells and canes are also used to visualize the flow of energy.

Of course; this will deviate from one fiction to the next, but generally this is how magic is used.

For a deus ex machina spell, should it be granted I would with good cheer accept the restraint.

(or could implement black the screen for no eyes, implement collisions, remove restricting boarders from pits and permit still the running blind while casting; this could get interesting lol)

btw only have seen harry potter.