Must the Creature (It is clear that that creature must Untapped and within 5 Squares), i want to use the for SHIELD card to prevent the damage on an other Creature, have a LOS to that creature?
The Distance and Counting Paragraph on Page 13 is not clear for me.
Yes you have to have line of sight. PG 13:
Some game effects, such as ranged attacks, creatures’ powers, and
some Order cards, specify a distance in squares (the distance to a
target or the range of an effect). Whenever you need to determine
distance, follow these rules.
* The acting creature must have line of sight to the target unless
otherwise specified (see “Line of Sight and Cover”).
* Count the most direct route along adjacent squares (they can be
diagonally adjacent), up to and including the target square. Don’t
count the acting creature’s square. (A creature that occupies more
than 1 square can start counting from any of those squares.) Difficult
terrain does not affect distance.
* Some effects specify a range in squares (such as “within 2 squares”).
When determining this distance, always count around walls, never
through them. If an effect states that it does not require line of
sight, you count through walls instead of around them.