Infiniti2000 said:
No, I am claiming that the directions of the arcs change when the direction of the creature changes.
Where does it state this? If this were really true, wouldn't it get called out in the Beholder arc rules especially considering that WotC took out the "facing" wording of Beholders for 3.5 (e.g. "straight ahead from the creature's front", "the beholder decides which way it will face", and "a beholder can bite only creatures to its front")?
The problem with your interpretation is that WotC explicitly took directional facing rules out of Beholders in 3.5 and this effectively puts them back in (with the exception of the bite). The Rays are free actions, so a Beholder could just spin around 270 degrees in his original square (which only takes up 3 squares of movement), never leave it, and fire all 10 of his rays at one target as per your interpretation.
But, it's clear from the text that WotC did not want Beholders to fire more than 3 rays in one direction (and effectively at one target).
During a single round, a creature can aim only two eye rays (gauth) or three eye rays (beholder) at targets in any one 90-degree arc (up, forward, backward, left, right, or down). The remaining eyes must aim at targets in other arcs, or not at all.
If one is allowed to change the directions of the arcs mid-round, these sentences make no sense. There is no significant reason for the first sentence to be there and no reason at all for the second sentence. Instead, they would have stated that you can turn the Beholder in order to place a new arc over the old arc.
Do you really think WotC added in the 3 eye rays per arc rule and the must aim at targets in other arcs rule, just to force Beholders to turn 90 degrees and use up one square of movement each time they want to move the next arc around to face their targets (the only downside at all in your interpretation)? Do you really believe that WotC added in these two sentences here (which really do not limit a Beholder in any significant way with your interpretation) when they really wanted to allow 10 rays to be targeted in one direction in a single round?
Do you really think they would have worded it this way for that?
Or, does it make more sense that they really wanted 3 rays per direction stationary arc so that a Beholder would have a tough time wasting an opponent (or an entire party) with 10 rays in a single round?
Honestly (be truthful), which makes more sense to you? Do you really think that 10 arcs in one direction was the intent of WotC with these sentences (and the removal of the facing text in the 3E to 3.5 central eye text)?
Note: With 4 adventurers in a standard party, the 10 rays from long range at all of the party members interpretation is begging for a TPK at the CR when a Beholder should first be encountered. Seriously, 3 Fort save rays and 7 Will save rays means that only Clerics, Druids, and Monks (and possibly Paladins) have any real decent saves against all of the rays. Every other class has weaknesses here. Even 13th level PCs would tend to have about +7 at best (shy of multiclassing or specific PrCs) with the weak saves and +14 with their best saves. Against DC 17, the chances of such PCs saving against 2 rays if it is a weak saving throw at +7 is 30%. That's 50% chance of failing one and 20% chance of failing them both.
With 10 rays versus 4 PCs (note: the stat block states 9, but the text states 10, so the text overrules a table), that's an average of 2.5 saves per PC. So on average, round one will typically affect if not take out 3 out of 4 PCs if the Beholder can fire all 10 rays at the party. And it will do it from upwards of 150 feet away (too far for most combatant types to charge into combat).
And with effects like Disintegrate, Finger of Death, Flesh to Stone, and Sleep, even allowing 3 of these in a round for 4 PCs is a potential disaster. Allowing all 4 of these plus 6 other spell effects every single round is a TPK just waiting to happen unless the party is much higher level than 13th. IMO.
Plus, these are rays. The ones that do damage can do double damage. And, they affect creatures at 150 feet, even though some of the spells they emulate have ranges of touch or close range. And, they are free actions. So, all 10 can be used in a Surprise Round.
Personally, I think you are totally ignoring WotC's intent and game balance in general with your interpretation. Again, IMO.
If you think me posting my honest opinion about something is being "antagonistic and passive aggressive", then you might want to consider putting me on ignore, because I'm not going to sugar coat things to avoid offending your delicate sensibilities. Especially when you make a thinly veiled dig at me, and then act all offended when I respond in kind. 
