D&D 5th Edition Data Explorer

Consume Life
As a bonus action, the will-o'-wisp can target one creature it can see within 5 ft. of it that has 0 hit points and is still alive. The target must succeed on a DC 10 Constitution saving throw against this magic or die. If the target dies, the will-o'-wisp regains 10 (3d6) hit points.
dc:
dc type:
CON
dc value:
10
success type:
none
Ephemeral
The will-o'-wisp can't wear or carry anything.
Incorporeal Movement
The will-o'-wisp can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
Variable Illumination
The will-o'-wisp sheds bright light in a 5- to 20-foot radius and dim light for an additional number of ft. equal to the chosen radius. The will-o'-wisp can alter the radius as a bonus action.