Crimson Sight

You smear blood across your eyes. For the duration, you can sense the presence of blood within 30 feet. If a creature with blood is within this range, you know the type (ex.: beast, dragon, giant, humanoid) and size of the creature, but not its identity.

Within the same radius, you can detect if blood was recently spilled. Traces of blood in a room and on objects that were present within the past 24 hours are revealed to you, even if the blood was cleaned. 

The spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt.

Bloodletting. When you cast this spell you can choose to expend a number of hit dice equal to the spell level at which it is cast. If one or more hit die are expended this way, the spell no longer requires concentration. 

At Higher Levels. You can target one additional creature within 30 feet of you for each spell slot level above 2.