Simple RAW 3

[Erys]

Q 350 Don't all spells require a clear path to the target unless they specify otherwise? Isn't Mearls wrawng about Eyebite and a Wall of Force?

A350: Short answer, kind of.

Long answer:

copy/paste from here:

There are three potential interpretations in play here:

1. One interpretation is that visual concealment is necessary for total cover, leaving targets on the other side of a wall of force, or a mundane transparency such as a floor-to-ceiling windowpane for that matter, fully targetable by spells and spell effects, or even mundane attacks (albeit with no guarantee of success).
2. Another interpretation is that even a transparent surface grants total cover, as it is a physical obstacle, albeit one unable to actually conceal a target.
3. The middle-of-the-road path is that spells can be targeted based on line of sight (including through magical and mundane transparent walls and surfaces).
   
   
   • Spell effects with physical components (fireballs, rays and such) behave like mundane projectiles and cannot pass through a transparent surface of any sort as a result, or are restricted in how they can pass through them.
   • Spells whose effects are immaterial (such as a mind-altering dominate spell) can freely traverse something transparent.

The applicable RAW is as follows (PHB p. 204):

A Clear Path To the Target

To target something, you must have a clear path to it, so it can't be behind total cover.

and (under Areas of Effect)

A spell's effect expands in straight lines from the point of origin. If no unblocked straight line extends from the point of origin to a location within the area of effect, that location isn't included in the spell's area. To block one of these imaginary lines, an obstruction must provide total cover, as explained in chapter 9.

Going to p. 196 of Chapter 9 of the PHB where total cover is defined:

A target with total cover can't be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.

Wall of force (p. 285) does not grant any concealment:

An invisible wall of force springs into existence at a point you choose within range. ...

However, since it is a barrier:

Nothing can physically pass through the wall.

it clearly meets the definition of obstacle, leading us off the end of the RAW, and into RAI territory.

I tend to play it where Wall of Force acts as full cover and protects you from spells like Eyebite; but Mearls interpretation is no less 'wrawg' than mine in this case.

Q354 illusion spell (any) blocks my vision of the enemy (cuz I failed my save, or just haven't he'd a chance to interact, etc). Can I target the enemy with a scorching ray spell? And if so, how would that play out? I can't see him, but I can target him? Attack at disadvantage? Perception check?

A354: Unless you have some means of targeting without using sight, no. You cannot target someone when said target is hidden from view.