Status Effects

Battle conditions (poison, sleep, burn) and an elemental type chart multiplying damage by matchup.

Why deferred: Both mechanics only create decisions when monsters have distinct kits and stats; with today's roster they'd be invisible complexity. The Status model (hp/exp) and the battle state machine would both grow meaningfully — worth doing once, after the foundations.

Revisit when: the roster grows beyond five species — attack power and defense and the roster's stat/kit differentiation have both shipped, so new species art is the remaining gate for a type chart to have enough matchups to matter.