OK, that breath weapon seems done. Move on to special abilities?
Sure!
We don't have anything to go on from the BECMI original.
We could crib from the
Monstrous Manual versions of Gold Dragon and Brown Dragon, which are supposedly rough-equivalents of the 2E Mystaran Brown.
In 3E, those have:
Brown Dragon
Sandstorm (Sp): Once per day, an adult brown dragon can create a vortex of violently churning sand at a distance up to 80 yards away. All creatures within a 60-foot radius of the center of the sandstorm take 1d6 points of damage each round they remain within the sandstorm. Characters in the swirling sands are blinded and must make a Balance check (DC 15) during each round they move more than 5 feet or fall prone.
Summon Huge Air Elemental (Sp): Once per day, an old brown dragon can cast
summon nature’s ally VII to summon one Huge air elemental, 1d3 Large air elementals, or 1d4+1 air elementals of smaller size.
Summon Greater Air Elemental (Sp): Once per day, an ancient brown dragon can cast
summon nature’s ally VIII to summon one greater air elemental, 1d3 Huge air elementals, or 1d4+1 air elementals of smaller size.
Other Spell-Like Abilities: 1/day—
create water, disintegrate.
Gold Dragon
Luck Bonus (Sp): Once per day an adult or older gold dragon can touch a gem, usually one embedded in the dragon’s hide, and enspell it to bring good luck. As long as the dragon carries the gem, it and every good creature in a 10-foot radius per age category of the dragon receives a +1 luck bonus on all saving throws and similar rolls, as for a
stone of good luck. If the dragon gives an enspelled gem to another creature, only that bearer gets the bonus. The effect lasts 1d3 hours plus 3 hours per age category of the dragon but ends if the gem is destroyed. This ability is the equivalent of a 2nd-level spell.
Detect Gems (Sp): An old or older gold dragon can use this ability three times per day. This is a divination effect similar to a
detect magic spell, except that it finds only gems. The dragon can scan a 60-degree arc each round: By concentrating for 1 round it knows if there are any gems within the arc; 2 rounds of concentration reveal the exact number of gems; and 3 rounds reveal their exact location, type, and value. This ability is the equivalent of a 2ndlevel spell.
Other Spell-Like Abilities: 3/day—
bless (juvenile or older); 1/day—
geas/quest (old or older),
sunburst (ancient or older),
foresight (great wyrm).