"Yes, proceed," Mark confirmed it with the system despite knowing how it is extremely useful for his growth.
If he had it, during the day, he could constantly absorb the natural energy from the surroundings and refine it into ether energy. His healing rate will increase by ten times. During the night, he could intrude into the palace and trouble his enemies all he wants. As he gets stronger, the effects will also get stronger.
Judging by how it is a part of set equipment if he somehow acquires other parts, he will receive some bonus buff for sure.
And yet, he gave it to Alina because he was a little bit lazy and doesn't want to do everything by himself. It is also one of the reasons he picked the summoner path instead of mage.
As Alina was as strong as 7-circle during the night, he was sure that no one would detect her whether she meets Feng Wu, assassinate his enemies, or even rob the treasury.