Veil of Neglect

Casting

You must mix several droplets of your own fresh blood with the ink or paint, immediately prior to casting this spell. You take 1d4 slashing damage to do so.

While casting this spell, you spend 2 hours using a paintbrush or your fingers to draw a surreal, labyrinthine structure with a perplexing sense of impossible spatial geometry on the object or creature that is the target of the spell. The target must be completely covered by the drawing for the spell to function properly. The spell can cover any target that takes 2 hours to draw the structure on—up to a medium-sized creature or a standard-size door. A smaller target requires more intricate, finer lines to be drawn. Due to the difficulty in effectively drawing the surreal structure on yourself, the spell cannot be cast on yourself.

Spell Effects

While the spell is active, the target is painted with the universe's "transparency texture." The target, while not technically invisible or insubstantial, goes unnoticed, ignored, or overlooked, as if filtered out of the perception of those around it. Creatures' eyes move past or skip over the target as if nothing is present. A door will be perceived as an uninteresting part of the surrounding wall. A creature or item will be overlooked but instinctually stepped around or stepped over.

A creature with high Passive Perception (suggested 15+, or 20+ at the DM's discretion) may notice something odd out of the corner of their eye, especially if they pass close to the veiled target. But when they turn to look, they no longer notice anything of interest. Should the creature choose to roll a Perception Check, they have to beat the spellcaster's Spell DC to pierce through the Veil. Using a mirror, still water, dark window, or other reflective surface grants creatures Advantage on Perception Checks to pierce through the Veil.

Similarly, should the Veil be cast on a creature, and that creature causes some disturbance to the environment (such as dropping or moving an object in a quiet, uncluttered room), other creatures in the room who notice the disturbance can roll a Perception Check, having to beat the spellcaster's Spell DC to pierce through the Veil.

Once the Veil has been pierced, the creature can see the Veiled target clearly. However, they note that the surreal drawing is disturbing to look at, and makes them want to look away. If the creature looks away or breaks line of sight for more than a moment (blinking does not count), or the Veiled target gains total cover from the creature, then the creature must immediately make an Intelligence Saving Throw against the spellcaster's Spell DC. If they succeed, they retain memory of the Veiled target and can perceive it immediately once it is back in their line of sight. If they fail, the Veiled target is once again filtered out of their perception, the creature forgets the details of what they saw (except for being aware they saw something odd), and another Perception Check will be needed to pierce the Veil again. However, future Intelligence Saving Throws are made with Advantage for the same Veiled target, regardless of whether the first was a success or failure.

If the Veiled target is a creature that casts a spell that directly affects other creatures, each affected creature may make an immediate Perception Check with Advantage. Likewise, if a creature is directed to look at the Veiled target by another creature who has currently pierced the Veil, that creature rolls Perception with Advantage.

The Veiled creature may interact with objects and the environment carefully, at risk of alerting nearby creatures. DMs are encouraged to force frequent Slight of Hand Checks for such "careful interactions", and frequent Perception Checks for nearby creatures. 

Any attacks made against the Veiled target are made with disadvantage, unless the attacking creature has successfully pierced the Veil at the time of the attack.

Ending the Spell

The complex drawing on the Veiled target is very fragile. Any damage to the target, or other permanent disruption to the drawing will cause the spell to end. Once the spell ends, the drawing fades or evaporates, leaving no physical trace.

A Veiled creature may move at its normal movement speed, but dashing, jumping, climbing, melee or ranged weapon attacks, or any other strenuous physical action that would smudge the drawing will result in the spell ending. 

If a Veiled creature passes perpendicular to a mirror, still water, dark window or other reflective surface, roll a Widsom Saving Throw against a suitable DC for avoiding their own reflection. On a success, the Veiled creature intentionally averts their eyes. If they fail, their gaze involuntarily seeks the peripheral movement in the reflection, and they immediately suffer 8d8 psychic damage due to filtering out perception of their own existence. The spell ends as they frantically rub or scratch at their own face. They are not affected when looking down at their own body normally, outside of reflections.

Notable Exceptions and Edge Cases

Creatures with Truesight are unaffected by the Veil of Neglect spell.

Magical (or other) recordings of a Veiled target affect viewers of the recording as if the spell is fully active, even if the spell has ended in real-time.

The Veil of Neglect spellcaster is also fully affected by the Veil of Neglect's effects, once they finish casting the spell and look away from the target. However, they maintain Advantage on Intelligence Saving Throws from the outset, and can recall casting the spell, even if they cannot perceive or recall the target.

Creatures that have enhanced senses, but still primarily rely on sight, are fully affected by the spell's effects. Their enhanced senses may allow a lower passive perception DC or a lower threshold of "noticeable" disturbance caused by the Veiled target.

Any creature with Blindsight can perceive the Veiled target without having to roll a Perception check while it remains within the range of their Blindsight. However, if the Veiled target leaves that range or gains total cover, the creature must make an Intelligence Saving Throw as described above to recall perceiving the Veiled target.

Divination magic that requires visual perception (See Invisibility, Clairvoyance, Arcane Eye, Scrying) is subject to the full spell effects, as above. Divination magic such as Locate Creature, Locate Object, Locate Plant or Animal, may direct the caster towards the Veiled target, if applicable, but will not otherwise assist in perceiving it. Detect Magic's "aura around a visible creature or object" is not effective, but it does allow the caster to identify that illusion magic is present, just not what or where it is cast. Detect Thoughts works as written, allowing the detection and reading of thoughts (if applicable), but does not otherwise assist in perceiving the target or finding its direction.