Ether clones aren’t substantial, let alone visible. Your clones can see each other, but light shouldn’t be able to affect them. So they wouldn’t show up in a reflection, or cast shadows.
Why, then, do you see two shadows right where the test clone should be? Is this an early sign of corruption, or is there something else nearby?
You can’t see the shadows from your own vantage point. Did the clone you had watching get corrupted instead? Or is this just a matter of perspective?
Perhaps the test clone can get a better look. You direct it to head to various points around the shadows. And you definitely see something.
It looks like the shadow of a night hunter. But there’s no actual hunter to be seen. It couldn’t both be hiding and casting a shadow, though…
So what if the shadow itself is moving? You focus your ether senses on the shadow, and indeed, it seems to be some form of light magic. An illusion, then?
No, because an illusion would not be able to rise up from the ground and grab your ether clone. There’s something more going on here, and it might just relate to the corruption.
But theories can wait. You should get that clone out of danger if at all possible.
Suggestions:
Suggestion on what this might be instead of light magic:
An ability specific to someone, a person or creature who is somehow able to manipulate shadows
Inverted light magic: bends visibility and presence in ways you’re not trained to handle. Not just illusion. Not just shadow. Something that uses both.
Getting the clone to safety:
Shoot a tether/lasso from your main mass like an arrow, piercing it with it should not harm it, or at least would be a better outcome
Manipulate light sources around the shadow, it might be an unnatural shadow but it should still be affected by light sources somehow, right? If not, then use a burst of light magic if possible
Send the clone vertically, the shadow might not be good at climbing