Fighter targeting is just as "mental" as spell targeting.
Yes, exactly! The fighter
targets whatever he mentally chooses with 100% certainty!
Whether or not he actually
hits his chosen target is determined by an attack roll.
When the fighter wants to whack the guy with
mirror image with his greatsword, he 'targets' the creature. In this case, the 'creature' is 'the guy with the images'. Then a roll is made to see if his target is shifted toward an image instead.
Exactly the same thing happens to an attacking caster with
fire bolt.
But a caster with
hold person has no chance of having his target switched to an image.
Why?
Conceptually, while the fighter and the caster of
fire bolt can mentally choose with 100% certainty to 'target' 'the guy with all the images', the attacks they are using must be aimed at the body mass of the target. They may aim at an image instead, since the images all look the same and are swirling around.
But the caster of
hold person/magic missile, while choosing to 'target' with 100% certainty 'the guy with all the images', those spells are not 'aimed' at all! Therefore, 'aiming at the wrong image' cannot happen.
Page 194 of the PHB. "Pick a target within your attack’s range: a creature, an object, or a location."
The exact same mental choice via "pick a target" as the spellcaster.
Absolutely! No argument here!
The important part is what happens next. Both a weapon and a spell involve time to actually form the attack against the target. If the spellcaster can still hit the target, so can the fighter. If one has to roll, both need to roll or it's a pile of nonsense. There is absolutely nothing in the spell section that says that a target is maintained after the caster looses track of it.
This drivel is just stuff you made up to be 'the important part'. It's not part of 5E.
Whether or not a spell needs to be precisely aimed at the body mass of the target depends on whether or not the spell requires an attack roll,
not that the spell has a target!
Maxperson, the upshot of your contribution to this thread is this: "If
I had written the
mirror image spell for 5E, I would have written it differently than Crawford did when he wrote the spell for the 5E PHB".
Fine. What's that got to do with anyone else? If we are at home or a convention when someone casts
magic missile at a guy protected by
mirror image, what should we do? Look at what the spell descriptions actually are? Or rule the same way that Maxperson would have ruled if Maxperson had his totally re-designed spell description included in the PHB?
We are going to look at what the spell description actually
is, not what the spell description
isn't!
It doesn't make sense to you because it doesn't match the way you would have written the spell. But the spells that are actually in the 5E PHB do not have to match the spell
you wrote in your house!
In 3E I loved
true strike. Plus 20 Insight bonus to attack and ignore all miss chances from concealment? Yes please! But I cannot come to the 5E forums and pretend that the 5E version of the spell works the same way. I wish it did, but it doesn't.
Similarly, I cannot bring the 3E version of
mirror image to the 5E forums and claim that the 5E version works the same way. It works differently now. You might like it, you might not, but you cannot pretend that it works the same way in 5E that it worked in 3E.