package Tie::Scalar::Battle;
my %pool;
our $attacker;

sub TIESCALAR {
    my ($class, $name, $health) = @_;
    return $pool{$self + 0} =
        bless { name => $name, health => $health }, $class;
}

sub DESTROY { delete $pool{shift() + 0} }

sub FETCH { shift->{health} }

sub STORE {
    my ($self, $value) = @_;
    die "$self->{name} died" if $value <= 0;
    my $old_value = $self->{health};
    $self->{health} = $value;
    if ($value < $old_value) {
        my $target = $attacker || (values %pool)[rand keys %pool];
        local $attacker = $self;
        # print "$target->{name}, $target->{health}\n";
        $target->STORE( $target->FETCH() - (1 + int rand 3) );
    }
    return $value;
}

package main;

tie $foo, 'Tie::Scalar::Battle', foo => 300;
tie $bar, 'Tie::Scalar::Battle', bar => 300;

# First punch
$foo--;