Take advantage of the opportunities afforded by this assassination to enjoy one of the most spectacular set pieces in the whole of Assassin's Creed: Unity.
Assassin's Creed: Unity guide - Sequence 11 Memory 2: Rise of the Assassin - La Touche
This is such a good mission. The huge crowd makes getting both opportunities easy, and the end result is brilliant - but getting the optional challenges can be hard, and it's very easy to thin the crowds too much while fooling about, so be careful.
- Three headshots
- Four cover kills
Assistance Opportunity - Crowd Assistance Available
Your target is out in the open in the middle of this crowded plaza, but don't rush in - get both available opportunities. To begin with, visit the merchant at one edge of the mission area and stock up on any supplies you're low on; if you have the cash, just hit the assassinate button at "consumables" to refill everything.
You have a good opportunity here to take out two guards with headshots; there are two just loitering in front of the crowd. Move off far enough away to one side so that only one of them can possibly see you, then pop him right in the bean. Wait for everything to go quiet, and repeat for the other side. If at any point you trigger an alert, draw the guards far away from the mission area, and try to get cover kills on them.
There are two opportunity objective markers in this area. One is on a cage full of prisoners, and the other is almost directly opposite it. This second one is where we're headed first. Head on up to the rooftops that mostly enclose the plaza, climbing up on the most west point. If you look around with Eagle Vision you should spot a sniper on a balcony looking out towards La Touche. Make sure he's not watching and climb in the window on the other side of this building and go into cover at his window. Say hello to cover kill one - and a much easier time of it when you eventually go down on the ground.
Get back up on the roof and trot south a little, looking for another two snipers. They're not anywhere near useful cover, unfortunately, and playing cat and mouse with them is not recommended, as they tend to alert everyone else, too. Take one or both out with headshots and you ought to have completed that optional challenge.
Take a look down at the street beneath you - not the plaza yet. You ought to see a patrolling guard. He passes by a door, so you get down there and into cover, then take him out for your second cover kill. Head into the building and take out the brute here with a vanilla stealth kill.
Use Eagle Vision and check out another building full of guards nearby. There's another guard here who will foolishly patrol near a door, so head in and score cover kill number three. You should now be pretty close to the crowd distraction objective. Thanks to your clearing out of snipers, you should only have one guard to worry about here. Use the crowd to get close, then sneak through an opening in his patrol to interact with the objective.
Assassination Opportunity - Steal the Key - Open the Cell
Now it's time to get the assassination done - with style. What I did here was head back into the building I'd already visited, then move into the streets outside the mission area, circling around it to end up on the other side, close to the cage full of prisoners that makes up the second objective marker.
Study the area around the cage form a distance and you'll spot a number of nearby guards who will need to be taken down with stealth kills out of sight. There's one guard you shouldn't kill, and he's the one that patrols between La Touche and the cage; there's nowhere really safe to drop him, so just leave him for last. If the cage is on the bottom point of the triangle formed by the meeting of two rows of buildings, the guards in the buildings on both sides of the triangle largely need to be cleared out. Luckily, they're pretty easy to take out with stealth kills and phantom blade headshots. Make sure you get your last cover kill, and headshots if necessary.
Once you clear out the two nearest buildings it's very easy to wait for the patrolling guard to wander back towards La Touche, then sneak up behind the two pairs of guards and double assassinate them, but I didn't even bother - I just crept past them and got to the cage.
After visiting the cage you'll be prompted to steal a key from a guard in the upper floor of one of the two buildings you just cleared out. Since everyone else is dead, this is very easy. You can pickpocket him if you like, but I stabbed him and looted his body.
Assassinate La Touche
This has been fun, hasn't it? Wait for a gap in the patrolling guard's vigil, then approach the cage again to kick off a cutscene and set piece. You can walk right up to La Touche, almost giving him a kiss, and then just quietly slip the hidden blade in.
Escape the Area
You have thinned out the forces here considerably, but not enough to make this a good place to hang around. Leg it away from the crowd, who only slow you down and provide no camouflage while freaking out, and escape your pursuers. Smoke bombs can be a big help here.