Mission 1: The Maroon Assassin
You'll find Anto in Kingston. Head to the first location and spot your targets. To eavesdrop on them, you need to be within range. As they move, follow them at a distance. When you see them stop, find cover or blend in to the nearest crowd to avoid detection.
Head to the second location and repeat the process. As they turn to the corner, they'll notice they're being followed and will run away. Chase after them and tackle at least one of them to complete the mission.
Mission 2: Recruiting Maroons
Once the mission starts, circle around the fence to the left then hang on it. Climb up and quickly jump leap at the two guards to kill them both instantly. Anto will take care of the guards in the entrance. Free up the prisoner and head to the next location.
The next nearest prisoner is escorted by four guards. You can have them distracted using the dancers or drunken pirates. You can also let them kill each other using berserk darts. Once you're ready, eliminate all of them and release the prisoner.
Head to the last location and take out the guards silently or cheaply using a well-placed smoke bomb. Either way, free up the last prisoner after taking out all the guards to complete the mission.
Mission 3: Under Attack
Meet up with Anto again and you'll be ambushed. Defeat the first wave, then Anto will tell you to find and defeat any one of the three groups of ambushers nearby. Do this until the waves are over and successfully repel their attacks.
Mission 4: The Commander's Ruse
As soon as the target appears, hire the nearby dancers and blend with them so you can tail the target at close distance. Continue following him until you reach the restricted area to the northeast.
Infiltrate the area and use your eagle vision to find the target in each of the search areas. Continue searching and moving in the green circles until you find the real target. Once you found him, tag him and make your move to assassinate him. It doesn't matter if you get seen after killing him; it will be just easier if you take him out when he least expected it. You'll obtain one of the templar keys from the target during the cutscene. Finally escape the area and become anonymous to complete the mission.
