Phantom Liberty where to start answer right below

[TheWhiteDeathKS]

If you are in the main story at ''NOCTURNE op55n1'' you will get the call for Phantom Liberty. The side quests are unnecessary.

SPOILER WARNING RIGHT BELOW!

If you are on the quest in the stadium later in the game.
If you let the bomb go off, you can shoot Reed at the landing platform that is supposed to take Song to the moon and Song will fly to the moon. King of Wands unlocks.
If you hand over song to Reed. King of Swords. For both, I would recommend saving the game so that you don't miss it as soon as you get to the landing platform.

If you choose the 2nd option at the stage, "Tell Reed" then you can continue playing until you are in front of the KERN, that's a wise ball, make a save there so you don't have to play the whole thing again. There you can choose Kill Song for ''King of Cups'' or leave Song alive for King of Pentacles

Have fun

[Spartan]

Im not even near nocturne but i have a quest saying phantom liberty. should i do it?

[Blackwolfe]

The phantom liberty dlc call comes after meeting Alt Cunningham pretty much.

Just continue with the questline for finding Evelyn, including the Gim and you'll get it. The phantom liberty quest pretty much tells you what main missions you need to follow. As a matter of fact, it will feel kind of natural moving into the PL stuff at that point.

Do not, for any reason click the spoiler unless you want to get Phantom Liberty stuff spoiled (by the looks of it, pretty spoilery spoilers for PL, I'm not that far myself, just finished the intro missions for PL)