Stun

Each time you are rattled (by a headbutt or stun attack) your state of consciousness becomes worse, lowering your mobility, attack and complexity. When it drops far enough, or your hit points drop below 1, you become unconscious and cannot act.

Stun State     Mobility   Attack   Complexity  Speed left
:::::::::::::: :::::::::  :::::::: ::::::::::  ::::::::::
Dazed           -2         -2        -1
Phased          -5         -5        -2         50%
Stunned         -10        -10       -5
Reeling         -15        -15       -10        12.5%
Blacking out    -20        -20       -20        6.25%
Unconscious     -100       -100      -50        3.125%, unable to act

You slowly recover over time (stunned becomes phased, then dazed, until you are Okay again). When someone uses 'aid' on you, you return to Okay at once. You cannot aid yourself.

Headbutt

'stun' is the same command as 'headbutt'; you need the headbutt skill. The stun skill only adds a passive bonus once above 75%. Headbutt can rattle a victim down to Blacking out, never straight to Unconscious.

If your victim is two or more size categories larger than you, your stun is more effective. If you lose the opposed headbutt roll, YOU are stunned instead.