If that is the case not only would you have the 3 rays at Logue you would fire 3 more from 4th arc at Bioran.
The example is not about that though. I'm trying to answer how the arcs work, not how to best reduce Bioran to a pile of dust. Obviously if you wanted to hit both characters, you could do so without moving or changing facing at all. But what I wanted to illustrate, is that the positioning of the arc does not change just because the monster changes facing.
Of course in this example I could have also drawn a pillar in between the Beholder and Bioran, so the Beholder has a reason to change position in order to hit him. But I did not want to clutter up the explanation too much with extra details.
First the facing argument here is an issue. In all versions before and after whenever facing is decreed, the facing follows the face of the creature. Just check out gaze weapons if you must, they are not 360 degrees.
But not when it comes to the ray attacks from the eyes. Facing only matters for the direction of the anti magic field from the central eye, which disables one arc. But it has no relevance to the arcs that determine which eyes can attack which player.
The creature creates the arcs and where he swings his eye determines that.
No, I think that is an incorrect way to describe it. Try and imagine it as areas of effect. The creature does not create the arcs, but they are spaces surrounding the Beholder that only a limited number of eye stalks can occupy. The rules try to simulate the fact that the 10 eye stalks aren't all on the same side of the creature, and thus they can't all attack in the same direction. The eye stalks can aim at any target within any of the arcs that I've illustrated, plus also up and down. But only three at a time in any arc, because just like in the illustration, the Beholder only has about 3 eyes on each side of its body.
In fact in some books state the arc (especially if the main eye is closed) can be driven like a line right through the beholder center. Thus getting 6 eyes blasting the party ahead (3 to the left of the center line and 3 to the right of the center line).
If this is true, it may only be true for older or newer versions of D&D. I don't remember ever reading it in the 3.5 PHB, DMG, Monster Manual, or even Lords of Madness. I try not to mix the rules of other versions. None of the descriptions of 3.5 Beholders that I've read make mention of being allowed to aim 6 eyes in the same arc. What you are describing is basically having two half-arcs face the party at the same time, so it can attack with 6 eyes simultaneously. That seems to be bending the rules to do exactly the opposite of what was intended.
In the above example two arcs are facing Bioran at the same time, which would technically allow the beholder to fire 6 eye rays at Bioran. Is this intended? I don't think it is. Its not like the beholder has 6 eye stalks growing on one side of its body all of a sudden. It should still only attack with 3 eyes in Bioran's direction. So I don't think you should be rotating the arcs to get two arcs to face one character. Just keep them like they are in my previous example, with one arc facing the target directly.
Now in the picture I lined up the target directly below the Beholder. Obviously if Bioran was south east of the Beholder, the arcs
WOULD be rotated like in this picture, so that again only one arc is attacking him.
When the eye is open you are forced to the arcs you have above. (Nice Pic by the way). So I could have a totally different arc if the eye is closed compared to the arc when it is open.
Thanks, you're welcome. I thought it would make the discussion a bit easier, so we're not talking past each other.
I don't think the Beholder has a totally different arc if the central eye is open or closed. I think if the central eye is open, it simply has one less arc that it can fire in. So with it's central eye closed, it can fire in 6 arcs, but if it is open, it can only fire in 5 arcs (because the one it is facing automatically cancels any magic effects, including its own). So for example in the top left example, if the central eye is open, then it can only fire in arcs 2,3,4,5,6, but not in 1. The arcs themselves, nor their position do not change, regardless of the facing of the creature, or whether its central is open or closed.