What does Four-Player Chess Board do in CK3?

Stress Gain -10% (patch 1.20.0.3).

How do you get Four-Player Chess Board with the console?

effect create_artifact_fp2_4p_chess_board_effect = { OWNER = root } — runs the scripted effect that makes it, for the character you play (debug mode).

Personal artifact · Trinket

Four-Player Chess Board

MasterworkThe Fate of Iberia

Four-Player Chess Board is a masterwork trinket artifact in Crusader Kings III: Stress Gain -10%. Quality 30 and wealth 30; maximum durability 75. It needs The Fate of Iberia. Patch 1.20.0.3, from game/common/scripted_effects/03_dlc_fp2_scripted_effects.txt.

Quick answers (2)

What does Four-Player Chess Board do in CK3?: Stress Gain -10% (patch 1.20.0.3).
How do you get Four-Player Chess Board with the console?: effect create_artifact_fp2_4p_chess_board_effect = { OWNER = root } — runs the scripted effect that makes it, for the character you play (debug mode).

When … beat … at chess, … first thought was to commemorate … gaming prowess by devising an improved variant so specific that … could never get anyone to play it.

Effects

Stress Gain-10%

How it is made

The game creates it with the scripted effect create_artifact_fp2_4p_chess_board_effect. In the console (how to open it), this gives it to the character you play:

effect create_artifact_fp2_4p_chess_board_effect = { OWNER = root }

Built from the effect's file; not run in the game by us.

Source: game/common/scripted_effects/03_dlc_fp2_scripted_effects.txt, common/modifiers (artifact_stress_gain_4_modifier) and the English localisation, Crusader Kings III 1.20.0.3.