[RPG] What space does the spell Cloud of Daggers fill

April 2016's Sage Advice expressly defines how this phrase operates and names Cloud of Daggers as one of several spells to which this definition applies.

In summary, a spell like moonbeam affects a creature when the creature passes into the spell’s area of effect and when the creature starts its turn there. You’re essentially creating a hazard on the battlefield.

Furthermore, it is stated that such spells do not damage targets when initially cast.

So this is how it works:

1. Daffy the Wizard casts Cloud of Daggers atop a mighty gorgon. The gorgon takes no damage. (You could say it is 'undeterred'.)

2. Garrosh, an orc barbarian, pushes a murloc into the Cloud of Daggers. The murloc takes damage (and shares the space with the gorgon).

3. The gorgon takes its turn and starts within the Cloud's effect, thus it takes damage. It wisely moves out of that area.

4. The murloc takes its turn and starts within the Cloud's effect, thus it takes damage. It chooses to remain in that space. On its next turn, it will take damage again. (Must be quite the murloc to still be alive.)

I did some digging into this particular question and I came up with these relative links.

First and foremost: This one about what happens if you lose line of sight

Followed by this very informative entry here on our very own Stack Exchange: About how you can keep concentration on a spell regardless of line of sight, range to the target(s) or AoE, or even plane of existence.

To answer your question directly, though; yes, there is nothing stopping you (neither in the spell description or rules on concentration and spell casting) from casting Call Lightning and then maintaining it's effects for a full 10 minutes even as your ship drifts away from the storm cloud.

For a more in depth look at the spell, here are a few key points.

• The cloud appears 100ft directly above you. No more, no less, and fails if you cannot see the point anywhere in the air/sky where said cloud will appear.
• When you cast the spell, and on each subsequent turn, a bolt of lightning flashes down to a point you can see within range (120ft of YOU not the cloud), and may target different points for each strike.
• If there is already stormy conditions in the area, you gain control over the existing storm, instead of making a new one (which also has the added benefit of increasing the damage).

I may be wrong (and anyone is free to leave potential corrections), but from all the above resources I've gathered, we seem to be able to conclude the following: You may cast Call Lightning and as long as you do not break concentration; you may continue to call down the full wrath of it's power for 10 minutes, even if you were to be taken to the Ethereal Plane (as per the spell Blink). You only require line of sight to the point you can see that you wish to strike each turn, and the spell only requires that point in question be within 120ft of you, not the 60ft cloud it summons forth.