I was thinking that that doesn't seem right, but I went to actually look at the description and you're right.Blindness absolutely stops all eye rays (except the central eye).
Eye Rays. The beholder shoots three of the following magical eye rays at random (reroll duplicates), choosing one to three targets it can see within 120 feet of it:
Blind beholder can't see anything, so the eye rays turn off.
Disintegrate says "This spell automatically disintegrates a Large or smaller nonmagical object or a creation of magical force. If the target is a Huge or larger object or creation of force, this spell disintegrates a 10-foot- cube portion of it." There's nothing about the forcecage spell that says it shouldn't work.As for the Forcecage, I believe the correct ruling would be that there is no rule basis under either the Disintegration effect of the Beholder or the Forcecage spell that would make it vulnerable to disintegration.
I disagree. A beholder's anti-magic ray works like an antimagic field, except cone-shaped. These would be the relevant parts of the description:With regards to what happens when the Beholder approaches the Forcecage wall with the central eye open and starts to try to pass through: This is not a situation covered by the rules. The 'partially within the spell' language applies only when the spell is cast. Accordingly, the adjudication of this interaction is up to the DM.
Spells and other magical effects, except those created by an artifact or a deity, are suppressed in the sphere and can't protrude into it.
[...]
Areas of Magic. The area of another spell or magical effect, such as fireball, can't extend into the sphere. If the sphere overlaps an area of magic, the part of the area that is covered by the sphere is suppressed. For example, the flames created by a wall of fire are suppressed within the sphere, creating a gap in the wall if the overlap is large enough.
The situation with forcecage is exactly the same as with wall of fire. The anti-magic cone creates a hole in the spell, but due to geometry the hole is not large enough for the beholder to leave.