You can Tribute this card to Tribute Summon a DARK monster.
You can't use this card as Synchro Material for a DARK monster.
While this card is on the field, you can Summon "Light and Darkness Dragon", but it can't attack.
You can Summon "Light and Darkness Dragon" while "Consecrated Light" is on the field. Once it is on the field, it will be unable to attack.