Blood Sight

3rd-Level Necromancy
Casting Time: 1 action
Range: Self
Components: VS
Duration: (C) 10 minutes

Your eyes to take on a crimson hue and for the duration, you can see the life force of nearby creatures. The range of this vision is dependent on your own vitality, and fluctuates with your injuries: 30 feet while at full hit points, 60 feet while lightly wounded, 90 feet while moderately wounded, 120 feet while heavily wounded, and 150 feet while critically wounded.
When a creature is at full health, they appear perfectly normal, but as they become more wounded a red aura begins to surround them. If a creature is wounded, you have advantage on Wisdom (Perception) checks to determine their location as long as you aren't blinded. If a creature is below 1/2 of its hit point maximum, you can see them even through walls, invisibility, and obscuring phenomenon such as darkness or thick fog. In addition, as a bonus action you can attempt to determine the exact amount of remaining hit points a single wounded creature within range has. In order to do so, you must succeed in a Medicine check using your casting stat. The DC of the check is equal to 10 + the CR or Level of the creature.
This spell has no effect on undead or constructs.
At Higher Levels. If you cast this spell using a spell slot of 5th level or higher, the duration is 1 hour. If you use a spell slot of 7th level or higher, the duration is 8 hours. If you use a spell slot of 9th level or higher, the duration is 24 hours. Using a spell slot of 5th level or higher grants a duration that doesn't require concentration.

Source: Homebrew