How does Belashyrra's Truesight interact with its Eye Thief ability?

Question

Eberron: Rising from the Last War includes a really interesting boss monster named Belashyrra.

Belashyrra has Truesight out to 120 feet:

A monster with truesight can, out to a specific range, see in normal and magical darkness, see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceive the original form of a shapechanger or a creature that is transformed by magic. Furthermore, the monster can see into the Ethereal Plane within the same range.

Belahsyrra also has a powerful ability called Eye Thief:

Belashyrra can see through the eyes of all creatures within 120 feet of it. It can use its Eye Ray through any creature within 120 feet of it, as though it were in that creature’s space.

The interaction of these two abilities, Truesight and Eye Thief, raises a couple questions:

• Does Belashyrra still have Truesight when viewing through another creature's eyes? This question is important for adjudicating an invisible creature behind total cover. Truesight let's you see invisible creatures, but if it doesn't apply when using Eye Thief, Belashyrra wouldn't be able to see an invisible creature behind total cover, even when looking through their eyes.

• If Truesight does work when viewing through another creature's eyes, is the 120 foot range measured still from Belashyrra's position, or the creature's?

Answer 1

It isn't totally clear

As with many things we ask about on this site, this answer isn't perfectly clear. We can look to other abilities to help guide us to answer, but we can also bring our expertise to the table as to what would be more fun and thematic based on the descriptions we have.

Similar mechanics

Find Familiar offers a specific set of wording that this ability does not:

Additionally, as an action, you can see through your familiar's eyes and hear what it hears until the start of your next turn, gaining the benefits of any special senses that the familiar has. During this time, you are deaf and blind with regard to your own senses.

Note that this spell differs from the creature's ability by adding the additional caveats and abilities.

Similarly, a caveat is added for beast sense that clarifies the use of the beast's senses over the caster's:

For the duration of the spell, you can use your action to see through the beast’s eyes and hear what it hears, and continue to do so until you use your action to return to your normal sense

With two examples showcasing the need for clarification about using the target's senses, the lack of additional constraints for Belashyrra moves the answer towards her able to use Truesight.

Belashyrra sees through their eyes

This is the bit where things get confusing. What does "sees through their eyes" mean? Does it mean similarly to find familiar? If so, why doesn't have the restrictions/abilities provided by that spell stated as well? If not, then is Belashyrra simply using their own sight through the eyes of the target?

The description only states:

Belashyrra can see through the eyes of all creatures within 120 feet of it.

While this can be interpreted both ways, thematically it fits better for Belashyrra to still be using their own eyesight and use their rays from the space the target is located in.

Range is 120' from the target's space

Belashyrra's ability also states (my emphasis):

It can use its Eye Ray through any creature within 120 feet of it, as though it were in that creature’s space.

The creature must be within 120' of Belashyrra, but the eye ray's target range is 120' from the creature from whom Belashyrra is viewing. While it's possible to read that this is only for the Eye Ray ability, that's a strange reading that it can see up to 120' for that ability, but not for anything else. If it can see that range for an Eye Ray, it can see that range.

Answer 2

In the absence of a clear statement within the ability description itself as to whether Eye Thief uses her own senses or the target's, we should interpret the ability in the most straightforward way.

Since it's specific that Belashyrra sees through the other creatures' eyes, I would think the most straightforward reading of that is that she sees exactly what those eyes can see, exactly as the creature sees it. That would means she does not gain the benefit of her Truesight unless she's using her own personal senses.

Answer 3

1st Question: it's up to the DM but likely no.

I see some links between this Eye Thief ability the Find Familiar spell (PHB, page 240), since they share a similar wording (emphasis mine):

Additionally, as an action, you can see through your familiar's eyes and hear what it hears until the start of your next turn, gaining the benefits of any special senses that the familiar has. During this time, you are deaf and blind with regard to your own senses.

In this case, it is explicitly stated that the caster gains only the benefits of the familiar and not its own (see here: credit to @Medix2). Belashyrra's Eye Thief ability has no explicit rule in this sense, hence the DM may decide in one way or another.

On the other hand, Eye Thief's description says (emphasis mine)

Belashyrra can see through the eyes of all creatures within 120 feet of it. It can use its Eye Ray through any creature within 120 feet of it, as though it were in that creature’s space.

There is hence an explicit ruling for a particular ability (Eye Ray), but nothing is said about Truesight: this leads to think that this latter does not couple with Eye Thief.

Personal note: using Truesight coupled with Eye Thief seems quite overpowered, in my humble opinion. But if the players (and the DM) wants an hard encounter, that's totally fine.

If Truesight couples with Eye Thief, the range is likely to be 120 ft. Again, up to the DM

Eye Thief's description says (emphasis mine)

Belashyrra can see through the eyes of all creatures within 120 feet of it. It can use its Eye Ray through any creature within 120 feet of it, as though it were in that creature’s space.

The emphasised words means that Belashyrra can see as it were in creature's space, I read this part as the Belashyrra's eyes are in place of creature's one, as it happens in Find Familiar spell. Again, this is not clearly formulated, hence the DM should decide.

Answer 4

DM's discretion.

The text here is really ambiguous. Two key statements stand out:

• Contra Truesight:

Belashyrra can see through the eyes of all creatures within 120 feet of it.

This implies, that Belashyrra uses the senses of the creatures, so it only has those available - if they don't have truesight, Belashyrra doesn't.

• Pro Truesight:

It can use its Eye Ray through any creature within 120 feet of it, as though it were in that creature’s space.

If Belashyrra would be in that creature's space, it would have truesight that would allow it to perceive and target an invisible creature.

However:

In my personal opinion the second statement is weaker and refers more to the origin of the Eye Ray than to the senses, while the first statement refers directly to the senses. So I personally would rule, that the Belashyrra can only use the senses of the creatures.