How does a spell resolve when the target changes places before the spell is finished?

Question

Here's what happened:

We've reached the end of the campaign, with only the last wave of minions standing between us and the dark sorcerer who's been flooding the local farms and villages with undead. As it comes to find out, literally the only thing between he and us were his minions. From the other side of the room, a perception check tells us that he's beginning to cast a spell. Spellcraft check tells the group wizard that it's an empowered chain-lightning spell, and after a quick taunt, he insures that it's him who will be the primary target of the spell.

Well, here's the hitch. He's prepared a dimension door spell, and has ready-action "teleport away if I'm attacked." The DM makes the call, and a spell that he knows will harm him falls under 'getting attacked' for the purposes of the condition of the readied action.

So, he teleports... behind the sorcerer. But, a few people in the group take issue with this. Here are the two sides of the argument, as they were presented in the group.

His side: The caster no longer knew where he was (this was also a topic of debate, but that's a different issue) and casters aren't allowed to choose 'that guy I know is within range of my spell, even though I have no idea where he is' after the rogue uses a ring of invisibility to vanish.

Other side: He was still within range of the spell, the spell caster had already chosen him as the target of the spell, and the spell specifically states that it goes from the caster's finger, to the target, and doesn't just affect an area.

Well, the GM ruled that, because of the specific circumstances, the spell would fail. The way he saw it, the lightning was shooting towards him, with him vanishing right before it hits him.

All that said, what is the actual rule on this? When a spell specifically targets a thing/creature, and then that thing/creature vanishes at the last instant, but stays within range of the spell, does the spell still activate? I can see this working for chain lightning, and other damaging spells, but what about spells like hold person?

This situation occurred while playing pathfinder, to be specific.

Answer 1

A spell is resolved - and the target is determined - when the spell comes into effect, not when spellcasting is "starting".

So in the example the sorcerer could still cast the spell, just another target would be determined if they are no longer aware of where the wizard is. The only way to stop the spell being cast (Spell resistance, saving throws, etc are another matter) would be to counterspell or disrupt (Concentration checks) the spell itself - removing the (intended) target before the spell is complete simply means that the caster (the sorcerer in this case) is free to choose a new target.

Ie. Even though the sorcerer had taunted the wizard the spell target hadn't yet been determined.

This is usually most relevant when a spell takes more than a simple action to cast (such as sleep, a one round to cast spell) but when reactionary effects get in the way spellcasters can still choose their target if their original one vanishes before their spell can take effect.

It's detailed in the Casting Time section of the Magic rules of Pathfinder, but the most important line of it is:

You make all pertinent decisions about a spell (range, target, area, effect, version, and so forth) when the spell comes into effect.

So, in the fraction of a moment where the wizard teleports away the spell's effect has not been determined - the wizard hasn't made a saving throw. So the sorcerer is still free to target anyone else they want. If there are no relevant targets of course (say, charm animal and all the animals vanish into the ether on a joyride) then obviously the spell will fail through lack of targets.

Answer 2

Readied actions happen immediately before the action that triggers them.

Characters have no facing in combat, and are assumed to be looking in all directions at all times.

Teleporting behind someone does not exclude you from their vision, nor does it make you an invalid target.

Therefore, what would happen is, the sorcerer attempts to cast Chain Lightning targeting the wizard. The wizard's readied action goes off, placing him behind the sorcerer. Then, the Chain Lightning goes off, targeting the wizard and dealing damage as normal. The wizard is now farther than 30 feet from his party members, so the Chain Lightning can no longer jump to any additional targets.

The spell has not fizzled, but the wizard's selfless action has spared his allies some damage.

Answer 3

Rereading my text, I think this is more of a philosophical/conceptual than a strict rules mindspin.

I see this as ultimately coming down to DM ruling. I can see how he reached his decision.

I just looked over both spells. The initial ranges are equal, though does the Chain Lightning have the upper hand as per level 6 vs 4. Chain lightning (CL) says it hits the target and then travels up to 30ft for the next target. One argument can be that the spell polarizes the target for the CL, and target is designated as the striking point. If the target should shift, then he is still designated the target as per magic rules. The CL would then attempt to reach his new location, at which point we get to a range race. Dimension Door (DD) and CL has the same range basis, but the CL already has a head start. If target were to DD outside the range of the CL, I'd call a fizzle.

Another way to look at it is - hit the spot where that dude is standing. So it is the spot not the person being hit. In which the consideration would be - The CL arces towards the target spot, and finds nothing. It will then try to reach the next target within 30ft. Again DM ruling, would the CL try to hit the same target that DD'ed out or would it hit a random within range. Again range race.

But as I started saying, I can also see the current DM ruling saying the spell fizzled.