# How can I tell a creature occupying more than one square is affected by an area spell?

In our last gaming session our enemies cast a silence spell. The bard had used Alter Self to a change into an Asabi, one of the few large humanoids. Two of his squares were inside the silence spell, two outside.

I recalled a rule that at least half of a creature has to be inside an area spell to be affected, but I could not find it. I wondered, if that was a 3E rule that had been revised. The only rule I could find was this one:

The point of origin of a spell is always a grid intersection. When determining whether a given creature is within the area of a spell, count out the distance from the point of origin in squares just as you do when moving a character or when determining the range for a ranged attack. The only difference is that instead of counting from the center of one square to the center of the next, you count from intersection to intersection. You can count diagonally across a square, but remember that every second diagonal counts as 2 squares of distance. If the far edge of a square is within the spell’s area, anything within that square is within the spell’s area.

So: is a creature affected by an area spell in DnD 3.5 if a single square of its space is within the area of effect? Or, if not: how many squares of a 4 square creature does it take to affect the creature?