Homebrew, Ravenloft: Denizens of Darkness (3.5e)
Ethereal Sight. The rushlight can see 60' into the Ethereal Plane when it is on the Material Plane, & vice versa.
Heated Body. A creature that touches the rushlight or hits it with a melee attack while within 5' of it takes 7 (2d6)
Illumination. When not invisible, the rushlight sheds bright light in a 10' radius & dim light for an additional 10'.
Incorporeal Movement. The rushlight can move through other creatures & objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.
Magic Resistance. The rushlight has advantage on saving throws against spells & other magical effects.
Turn Resistance. The rushlight has advantage on saving throws against any effect that turns undead.
Undead Nature. The rushlight doesn't require air, food, drink, or sleep.
Flame Touch. Melee Weapon Attack: +7 to hit, reach 5+, one target. Hit: 18 (4d6 + 4) fire damage. The target must make a DC 15 Dexterity saving throw or be ignited with magical fire. An ignited creature takes 7 (2d6) fire damage at the end of its turn. The rushlight's fire can be extinguished with a casting of the Dispel Magic, Remove Curse, or similar magic, or if an action is used to douse the ignited creature with holy water.
Etherealness. The rushlight enters the Ethereal Plane from the Material Plane, or vice versa. It is visible on the Material Plane while it is in the Border Ethereal, and vice versa, yet it can't affect or be affected by anything on the other plane.
Invisibility. The rushlight turns invisible until its concentration ends (as if concentrating on a spell).
Any climate; any terrain