If you are obsessed with saving space, you could do something like:

# In case you want to access the array mnemonically.
# Depending on your version of perl, you might need to
# declare one constant at a time.
use constant {
  BOOK => 0, BEHOLDER => 1, PAGE => 2
};

my $MM = "Monstrous Manual";

my %monster_lookup = (
'beholder' => [$MM, 1, 21],
'death kiss' => [$MM, 0, 21],
'eye of the deep' => [$MM, 0, 21],
#etc...
);

my $monster_type = 'beholder';
my $monster = $monster_lookup{$monster_type};

printf "Monster: %s Book: %s Beholder: %s Page: %s\n", $monster_type, 
+@$monster;

# E.g. accessing one attribute at a time
print "$monster->[BOOK]\n";
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