Boss tactics Updated Sep 27, 2026
The Physicist is the Underpass Resonant at the top of The Spire. Reaching it is harder than the fight: three unmarked Astral Keys open three doors before the arena. Rewards: Spike or Astral Rebuke + Untapped Golden Earrings recipe.
Route
- Open the Underpass via Recursions and Iterations (Reach required) — Subway Fault.
- At The Spire, use Shift onto the red-carpeted wall and climb.
- Clear enemies to unlock the next Astral Plane section.
- Collect three Astral Keys (east, north, south of the door hub — not on minimap).
- Unlock all three doors, then enter the Physicist arena.
Fight tips
- Punish short windows — greedy full combos get you hit.
- After an attack, dash in for a few hits, then withdraw.
- Burn / status builds melt it faster; both rewards apply Astralized (other statuses stack quicker).
- Later phases: side-dodge ground spike waves; when it slams and pulses, attack on wind-up then dash sideways as spikes erupt underfoot.
- Copies appear mid-fight — clear them before the main body returns with new patterns.
Spike or Astral Rebuke?
- Spike — summon Astral orb pressure / knockdown; better for summon-style kits.
- Astral Rebuke — homing lift on grounded targets; simpler melee disrupt.
Deep dive: Spike vs Astral Rebuke. Astral Reconfiguration trophy pops when the full key sequence + kill register.
Related: Underpass Fault · Boss hub · Combat