sub team_battle { # pit three players against three other players
    my @opp = grep { $rps{$_}{online} } keys(%rps);
    return if @opp < 6;
    splice(@opp,int(rand(@opp)),1) while @opp > 6;
    fisher_yates_shuffle(\@opp);
    my $mysum = itemsum($opp[0],1) + itemsum($opp[1],1) + itemsum($opp[2],1);
    my $oppsum = itemsum($opp[3],1) + itemsum($opp[4],1) + itemsum($opp[5],1);
    my $gain = $rps{$opp[0]}{next};
    for my $p (1,2) {
        $gain = $rps{$opp[$p]}{next} if $gain > $rps{$opp[$p]}{next};
    }
    $gain = int($gain*.20);
    my $myroll = int(rand($mysum));
    my $opproll = int(rand($oppsum));
    if ($myroll >= $opproll) {
        chanmsg(clog("$opp[0], $opp[1], and $opp[2] [$myroll/$mysum] have ".
                     "team battled $opp[3], $opp[4], and $opp[5] [$opproll/".
                     "$oppsum] and won! ".duration($gain)." is removed from ".
                     "their clocks."));
        $rps{$opp[0]}{next} -= $gain;
        $rps{$opp[1]}{next} -= $gain;
        $rps{$opp[2]}{next} -= $gain;
    }
    else {
        chanmsg(clog("$opp[0], $opp[1], and $opp[2] [$myroll/$mysum] have ".
                     "team battled $opp[3], $opp[4], and $opp[5] [$opproll/".
                     "$oppsum] and lost! ".duration($gain)." is added to ".
                     "their clocks."));
        $rps{$opp[0]}{next} += $gain;
        $rps{$opp[1]}{next} += $gain;
        $rps{$opp[2]}{next} += $gain;
    }
}