alright, so ser mandon moore's ability allows him to be brought out of the shadows as part of a Challenges: action. my question is, does this use up your one one card out of shadows per phase limit or can i still bring someone out at the normal time.

The rules only allow you to bring one card out of Shadows at the beginning of each phase.

That's not the same thing as limiting you to only one card coming out of Shadows each phase. If you have some other card effect (like Ser Mandon Moore's) that will bring another card out of Shadows apart from the one you bring out by the Shadows rules, go right ahead.

It's like the rules allowing you to initiate just one military challenge each Challenge phase, but card effects allowing you to initiate more apart from the one the rules give you.