A dark power

When I wake up, thinking to use my ability that showed the way out of the caves with glowing footprints, I focus on the elven woman who absconded with Savaeris's holy symbol.
A searing pain wracks my brain, and I am barely able to detect a glow from the tower before collapsing to the ground.
When the pain fades, I notice my right hand has become corrupted.
The veins are darkened and varicose.
 
I decide it's probably not wise to use this "gift," at least not to track members of the death cult.