This is one of the Area Effects of Super Dungeon Explore.

A Lance effect draws a straight line directly away from the user's square along a distance of X.  Every model along this line is hit.  Lance effects may not be used along diagonals and replace the distance portion (X) of a distance effect, but do not replace any other aspect of the ability.

As of version 1.5 of the rules, all effects require line of sight, so spray only effects models in squares that the user has line of sight to.