if(sd->status.party_id && (skill2_lv=pc->checkskill(sd,TK_POWER)) > 0) {
if( (i = party->foreachsamemap(party->sub_count, sd, 0)) > 1 )
damage += 2 * skill2_lv * i * (damage /*+ unknown value*/) / 100 /*+ unknown value*/;
}


and 


if(sd->status.party_id && (temp=pc->checkskill(sd,TK_POWER)) > 0){
if( (i = party->foreachsamemap(party->sub_count, sd, 0)) > 1 ) // exclude the player himself [Inkfish]
ATK_ADDRATE(2*temp*i);
}