This plain white wax candle can burn every day without diminishing.
Wondrous Item 25,000 gp
This candle sheds dim light 2 squares in all directions and never burns down (but can be extinguished).
Power Daily (Standard Action)
Use this power while the candle is lit. Until the end of the encounter, creatures within 2 squares of the candle lose the insubstantial quality and can't become invisible.
Published in Adventurer's Vault 2, page(s) 76.