Mutated Lucas

Chapter: NaH · Not a Hero · Salt Mines and Lab
Where: Research Facility, Cultivation Lab: central machinery and 2 green-lit wall oxygen tanks

Weak point

The head (it glows red) until he goes into shock; then the chest

The final boss of Not a Hero. He has 28,000 HP and cuts damage by 75–85% except on the chest; grenades ignore that penalty. The loop: head until he goes into shock, then RAMRODs into the chest. He is invulnerable while he recovers from his drop and while he roars. Smash every crate first: on Normal there are 2 Strong Med Injectors on the east desk, 48 shotgun shells + 20 handgun rounds on the NE desk and RAMROD ×2 on the edge of the central machinery.

Reward

Chris finishes him with a shotgun blast and destroys his computer: the end of Not a Hero.

28,000 HP (datamined). Base damage on Normal: bullet 500, RAMROD 2500; Incendiary Grenade about 1200–1320, Neuro-stun 500–620, Grenade 300. On Professional the deflect window is narrower. One guide says the chest stays exposed in phase 2 without another shock; another says you repeat the loop.

Step by step

Phase 1: shoot his head with the handgun or the shotgun on normal ammo until he goes into shock. Save the RAMRODs.
In shock his chest opens: about 5–6 RAMRODs' worth of damage there starts phase 2.
Deflect (L right before the hit) his close attacks: the vertical slam, the horizontal right-tentacle strike (you can also crouch under it), the slow jab and the backhand. His grab kills instantly unless you block or deflect it; a deflected grab puts him straight into shock.
The mid-range spinning jump attack can't be deflected: sprint to one side or get behind cover. The 3–4 hit combo can end in the grab: keep your distance or deflect.
An Incendiary Grenade always stuns him, as long as he isn't already flinching.
Phase 2: he jumps onto the central structure and mutates his arms. The spores drain your oxygen even with the High-Grade Filter: refill at the 2 green-lit wall tanks, only at about 10–30%, because they recharge slowly.
Repeat head → shock → chest; now he shields his chest with an arm, so don't shoot the arm. He attacks as he lands when he jumps off the structure (don't stand close), and fires an acid stream from his left hand: take cover, or get close and crouch.
Kite him around the corners of the machinery so he never has a straight line to you.