Albert Wesker (Monarch Room)

Chapter: 5-3 · Uroboros Research Facility
Where: Monarch Room: a large hall with two staircases and pillars. The door on the right (east) opens a loop of upstairs corridors with jars, the L. Hawk sarcophagus and treasures.

Weak point

Wesker: his back, once he has lost track of you (he says "You can't hide forever" or "Just accept your fate"). 3 shots per opening at most. Jill: the P30 device on her chest; kill Jill and you lose.

Wesker says he only has seven minutes, and the masked Jill fights on his side. There are two routes: survive the 7:00 by dodging (he leaves on his own), or make him flee early by beating him down, which gives the Heart of Africa (₦10,000) and the Bad Blood award. Then comes phase 2: Jill alone, and you must tear the device off her chest.

Wesker dodges every shot he sees coming. You only land hits once he has lost you: break his line of sight, wait at a corner near him, step out, shoot his back with your best gun and run before he warps and rushes you.

Reward

Heart of Africa (₦10,000) and Bad Blood if Wesker flees before 7:00. Masters of Removing for pulling the device together. The L. Hawk from the sarcophagus is added to the shop. Wesker and Jill (Brainwashed) figurines: 10 BSAA Emblems and Chapter 5 cleared.

Difficulty: on the harder settings he dodges more, and his gunshot can put you straight into DYING.
Jill in phase 1: fires SMG bursts (dodge prompts). With your partner you can knock her down; she gets up after about 2 minutes. Solo, IGN suggests leaving AI Sheva with no gun or only the Stun Rod to handle her.
Jill in phase 2: backflips to mid-room and sprays two SMGs in a circle (no prompt: hide behind a pillar or circle close to her), shoots from the top of the pillars (stand under her or behind another pillar), leaps into a suplex (get out of the way) and trips you. It takes at least 3 attempts.
Solo, AI Sheva hits the device reliably when you restrain Jill.

Step by step

Loot first: run to the door on the right and examine it; after a few seconds Wesker kicks you through it (cutscene). Upstairs: jars, the Sapphire (Oval) and the sarcophagus (your partner opens it) with the L. Hawk, the Emerald (Oval) and the Sapphire (Brilliant); at the far end of the east balcony, the Emerald (Brilliant). Grab it all before Wesker leaves.
Easy route: dodge, keep away and use the corridors to break his line of sight until 7:00 runs out.
Heart of Africa route: lure him to the north-west rooms, wait out of sight, shoot his back (3 shots at most: on the 4th he charges you, with a counter prompt) and get away.
When he staggers, do the combo (Xbox: X, X, B, A, then X+A; PlayStation: Square, Square, Circle, X, then Square+X). One wrong press = an unblockable kick; too slow and he draws his gun (dodgeable, very damaging shot). One source counts about 5 magnum shots in total.
In co-op, one player baits him while the other shoots his back. A Rocket Launcher from behind the kicked-in door also works if he doesn't dodge; if he catches the rocket, shoot it with a handgun while he holds it.
If he flees early, the Heart of Africa lies on the floor between the two staircases at the start of phase 2: take it before removing Jill's device.
Phase 2 (Jill): as Chris, circle her until the "Entreat" prompt appears: the device shocks her and she stops. Grab her from behind and mash; Sheva shoots the device or pulls it off.
Every gun does the same damage to the device: in co-op use the weakest one, and never magnums, rifles or explosives near her. Hit her body too often and she dies and you lose. "Get the device!" with heavy sparking = the last pull.
For Masters of Removing: one player holds Jill standing while the other, from the front, tears the device off.