Mission 30 -
Kill Roy's Enforcers
Kill Nestor Pellegrini.
Just a few footfalls from your quest giver, so jog over and take him out. Well, jog and swim. Approach from the water, swimming past the compound and coming ashore at the heavily crated area.
Then it's your standard game of crouch & whistle. Be careful crouching by the small cement ramps leading into the building, though- the slight height difference may prevent a stealth attack against exiting enemies
Kill Fabio 'Fab' Fulci
Fab and his boys have taken the underworld motif a bit too literally. Follow the objective marker to ladder down beneath the streets.
Follow the corridor to the large chamber, and take up position on the left side of the arch before whistling in trouble.
Lure in the near guards, and advance to the water. If you've brought a sniper rifle, the rest is easy pickings- just be sure, as per standard protocol, to kill the sentry first. The other enemies will generally be confounded by the water barrier, and you'll be able to pick them off at your leisure. If you're rifleless, sneak along the left hand wall until you can take out the nearer targets by pistol. The Sentry tends to hang out to the extreme left- make sure to tag him before jumping into the water and swimming across.
However, if it's a choice between Fab and the sentry, kill Fab. Reinforcements can be easily lost in the sewers, but if Fab is spooked he'll flee topside, and assassinations are a lot trickier in broad daylight. If you do find yourself in this bind, attempt to whistle-lure him behind some nearby cover that's hidden from public view.
Before you leave the sewers, you might also pick up the fuses that are on wooden tables on both sides of the water.