(Hemomancy)
You draw out a portion of your blood, causing your eyes to take on a crimson hue. For the duration, you can see the life force of nearby creatures. The range of this vision is a number of feet equal to 5 times the number of hit points spent on this spell.
When a creature is at full health, they appear perfectly normal, but as they become more wounded a red aura begins to surround them. You can notice when a creature’s current hit points are below one of these three thresholds: 3/4, 1/2, or 1/4 of their hit point maximum. Once a creature is below 1/4 of their hit point maximum, you can see them even through walls and invisibility.