Dimension lock and plane-shifting spells

[banana-for-ever]

Wondering something - if two teams have mages, and on the first round one of them sets a quickened dimension lock prepared on a ready action, then the other mage uses dimension door. When you cast dimension door, you walk your way through the ethereal plane, so you at least take one or two steps, it should take like a second at least. If the first mage casts his quickened dimension lock at this moment, does the second one get trapped in the ethereal plane for the duration of the spell? We already figured that if you use dimensional anchor or dimension lock on a creature under the blink spell, since you have 20% chance of hitting the creature while it is in the ethereal plane, there should be a 20% chance it gets locked there instead of on the material plane. But can it affect a dimension door if timed with a ready action?

[Necroticplague]

Spells on the Material Plane don't extend to the Ethereal, so you can't hit something on the Ethereal with DL (barring specific corner cases of which this is not). So your statement about blink is flat out wrong, you either trap him on the Material, or you miss him as your bolt hits where he used to be.

Now, onto the question about DD:No. But this is more about the rules for readied actions than the ones for spells.

If the triggered action is part of another character’s activities, you interrupt the other character. Assuming he is still capable of doing so, he continues his actions once you complete your readied action. Your initiative result changes. For the rest of the encounter, your initiative result is the count on which you took the readied action, and you act immediately ahead of the character whose action triggered your readied action.

So if you readied an action to cast DL on someone when they DD'd, the event would play out as follows:
1.They begin to cast.
2.You interrupt them before they make the jump, casting DL on them.
3.They finish their action (casting DD), and their spell fizzles (since they are prevented from casting it).

[Andion Isurand]

Abjuration spells and effects on the material plane typically extend to the ethereal plane like force effects do.

http://www.d20srd.org/srd/planes.htm#theEtherealPlane

In addition, teleportation spells and effects typically involve the astral plane.

http://www.d20srd.org/srd/magicOverview/spellDescriptions.htm#teleportation

[holywhippet]

So if you readied an action to cast DL on someone when they DD'd, the event would play out as follows:
1.They begin to cast.
2.You interrupt them before they make the jump, casting DL on them.
3.They finish their action (casting DD), and their spell fizzles (since they are prevented from casting it).

Not quite. You'd need to make and succeed in a spellcraft check to tell that the caster is in fact casting dimension door I'd have thought. Your DM might let you cast it anyway if you fail the check and assume that is what they are casting.

The target could possibly get around the problem if they have the mobile spell casting feat from complete adventurer and move out of the dimension lock area before they finish the spell.

[Crake]

I don't know where you got the impression that dimension door utilized the ethereal plane at all. It uses the astral plane, and even then, the caster merely bends the astral plane to create an instantaneous path from point A to point B on the material plane, so there is no percievable time spent there (although it is long enough to break anything that requires a constant line of effect to a target). But for all other intents and purposes, the caster of a teleportation spell disappears and reappears immediately upon completion of casting the spell.

Edit: Think of it like folding a piece of paper. The paper is the material plane, the space around the paper is the astral plane, the two parts of the paper are touching, there may as well not be any space between them, same with teleportation spells, there is no "step or two" on the astral plane.

It is also worth noting that both dimensional anchor and lock say that they do not affect creatures already ethereal, so in the case of dimensional anchor vs a blinking target, if you hit them while ethereal, the spell has no effect, although with dimensional lock, once they return to the material plane, they'd be affected by the lock and stop blinking (but be on the material plane).