Can Truesight see-through Shadow of moil 5e? What are the advantages?

Shadow of Moil 5e is the only way to detect Truesight, Blindsight, and Tremor Sense in dnd 5e. Truesight can see through the darkness, even the Shadow of Moil. Truesight doesn’t see through physical concealments such as that created by a dense Sandstorm or blanket.

Let’s take it down to the essential facts.

True Sight lets you see in darkness without any penalty, mundane or magic.
The spell creates an area that is darkened and magical.

True Sight is a condition that allows you to see creatures under the Shadow of Moil effects without any penalty. It doesn’t matter that the spell mentions “flame-like Shadows,” as shadows are a specific type of darkness. TrueSight only cares that the area is dark and that it was created magically or naturally.

Shadow of Moil 5e is Very obscure. Let’s know the spell.

Shadow of Moil, a necromancy spell of 4th level with the following description (XGtE p. 164): Your body is covered in flame-like shadows that surround it until the spell is over. Within 10 feet, the shadows transform dim light into darkness and bright light within the same area into the dim light. Shadow of Moil can greatly obscure you. You also experience a dimming of the light around your eyes.

Source: Xanathar’s Guide to Everything
Spell lists. Warlock

4th-level necromancy
Casting Time: 1 Action
Self-Reporting Range

Components: V (an undead eyeball wrapped in a gem of at least 150gp) and S, M (a component made from V, S, and M).
Duration: Concentration up to one minute
You are immune to radiant damage until the spell ends. Additionally, if a creature is within 10 feet of your target, the shadows will lash out at it, inflicting 2d8 necrotic injury.

Truesight 5e dnd core rule (PHB p. 185)

Truesight is the ability to see beyond a specific range of light and see invisible objects and creatures. It also allows you to automatically detect visual illusions, make saving throws against them and see the original form and appearance of shapechangers or magical creatures. The monster can also see into the Ethereal Plane.

Truesight can see through illusions and darkness, but it cannot see through magically conjured objects. Fog Cloud is a spell that would work against Truesight. The fog is not conjured as an illusion but is created into physical existence.

It is now up to you to decide if the “flame-like shadows” are tangible objects that can block your line of sight or if they are illusions or magic darkness.

The “flame-like shadows” spell doesn’t specify that they are illusory, so I think it is unlikely that they are illusions. They are also dissimilar to effects illusion spells in that the flame-like shadows can deal necrotic damage. In contrast, most damage-dealing illusions, except for Illusory Dragon, can deal with psychic damage. Because they are so dark that they obscure the user’s view, even against darkvision, they are not considered a form of darkness. This interpretation is supported because “Flame-like Shadows” first describe how they obscure the user. It says that they decrease the light around them. Shadow of Moil’s spell Darkness does not specify that darkvision can help it. Still, it does not mean that darkvision is effective against its darkness.

Truesight is not affected by shadows because they are neither darkness nor illusion.

Is Shadow of Moil 5e magical darkness?

Level 9: Choose synaptic static to replace both. Shadow of moyle can be a magical effect. However, it is limited in its ability to create complete darkness. It states explicitly that your normal light will turn dim and you will become darkened entirely within 10 feet.

Shadow of Moil (XGtE) requires an undead eyeball within a gem (worth at minimum 150 gp) to be its material component. Does the Shadow of Moil consume the gem?

An undead eyeball

The act of acquiring an undead eyeball seems trivial to the evil necromancer. Kill someone, animate them using Animate Dead, and then take an eyeball from your new friend.

I have interpreted this requirement to refer to the eyeball of an undead entity and not an eyeball that is animate. However, it is a staple of undead tropery that each of the severed parts remains independently animate. Let’s hope you can still get an animated undead eyeball through this procedure.

In a gem-encasement

This part should be manageable with one large, costly gem (not exceeding 1ft in size), a set of jeweler’s tools, and the Mending Cantrip. Split the gemstone with one clean cut. Create a space within the gemstone that is large enough to hold your undead eyeball. Press the two halves together and use Mending to close the hole. You can only repair one break or tear at once with Mending. If you can do this, the other half of your gemstone will be sealed. Voila! An undead eyeball wrapped in a gem.

It might be a good idea to hire someone proficient in jeweler’s tools for this task. Making a clean break can be difficult for someone who waves a hammer around and doesn’t know what they are doing.

What happens when a PC casts darkness or shadows on Moil and a dragon has Blindsight?

“A heavily obscured area” is created by darkness.

In an unofficial clarification on Twitter, Jeremy Crawford addressed the distinction between that and Shadows of Moil.

Shadow of Moil can completely obscure you. You also experience a dimming effect from the spell. You are not in darkness, but the flame-like shadows around you cause you to be heavily obscured. That means that you are entirely obscured from darkvision. #DnD

Heavy obscurement means:

An area that is densely covered with foliage, darkness, or opaque fog blocks vision completely. A creature effectively suffers from the Blinded condition (appendix B). (PHB, 183)

The blinded condition is:

Blinded creatures can’t see, so automatically fail any ability checks that require Sight. Attack rolls against them have an advantage, and their Attack rolls against them have disadvantages. (PHB, App A)

That is how Darkness, Shadow of Moil, and Darkness work:

You create the Blinded condition for your foe. Blindness does not per-target in the conditions text), it is clear enough what they are saying.

Blindsight allows a creature to see its surroundings and not rely on Sight. Blindsight can still be used to see the world, even if Darkness or Shadows of Moil blind them. However, there is no penalty for being blinded if they live within their blindsight zone.

That is why Shadow of Moil and Darkness does not affect creatures with Blindsight. It blinds it, but it doesn’t matter. (There are exceptions for corner cases, such as a deafened bat or as the DM determines.

Is Shadow of Moil a way to give the user an advantage over enemies? How does Shadow of Moil work on an area that is heavily obscured?

You are not in darkness, but the flame-like shadows around you cause you to be heavily obscured. That means that you are entirely obscured from darkvision.

Shadow of Moil is a spell that blinds enemies when cast on themselves. You are considered an invisible attacker or target, and you gain an advantage in attacks against enemies. Enemies get disadvantageous when you attack them.

This spell should work for creatures with darkvision because it clearly states that you will become significantly obscured from others. That is not clear, however, as the following sentence says, “The shadows transform dim light within 10 yards of you into darkness, bright light in that same area to dim lighting.” It is implied that it’s obscured because of magical darkness.

PHB errata clarifies that in heavily obscured areas (e.g., You are effectively blinded when you see other creatures in dark places)

Read Toril Map 5e