Close burst from a large creature — one square origin or all of them

Question

If a large or larger creature uses a close burst, does the burst have to emanate from a single square of the large creature's space, or does it act as if the creature is the source (all squares)?

The situation came up when a controller cast a close burst that emanates from the target's square as an effect. The target was large and the GM ruled that the burst emanates from one of the squares the target occupies. Caster's choice as to which square.

Answer 1

According to page 109 of the rules compendium:

A burst starts in an origin square

and gives an example for a burst 2:

extends 2 squares in every direction from its origin square: for a Medium creature, a 5-square by 5-square area

Since it bothers to specify the size of the creature in the example, I think we can imply a lot from that. However, it is made clearer elsewhere…

Page 99 and onwards describe what "origin square" means for various types of power. I'll quote Ranged:

The ranged power of a Large create, such as a beholder, has an origin square of 2 squares by 2 squares

I think it is fairly clear that it would start in all the squares occupied by the creature and extend outwards from there. So the large creature using the power in the example above would have a 2x2 origin square and extend 2 squares in each direction from there, covering 6x6 in total.

Answer 2

More citations from DDI:

Origin Square: A close attack’s area of effect defines the attack’s origin square, which is the attack’s starting point. A close burst uses your space as its origin square. A close blast uses a square within your space as its origin square. For a target to be affected by a close attack, there must be line of effect from the origin square to the target.

Burst

A burst starts in an origin square and extends in all directions to a specified number of squares from the origin square.

Consensus on the forums agrees with corewolder (though the comment about mounts is strictly wrong)

And after a while of searching, there doesn't seem to be any contradiction other than the slight one offered by mount and rider which, after some thought, supports the concept that the originating creature's occupied space or spaces is the origin.

Answer 3

To answer the question posed in the comment, we look at the mount and rider rules. It's clear that the originating creature creates the power. Thus, as spirit of hawk's wind doesn't "originate" from the target creature as per its wording, the player must choose a center square from which the burst will originate.