Monsters

Breath Weapon (Su): Either a cone of cold 50x50x50 feet long or a cone of paralyzing gas 50x50x50 feet long. It cannot use either breath weapon until 1d4 rounds later. Cold damage 18d8, Reflex half DC 31; gas damage Fortitude save (DC 31) or be paralyzed for 1d6+9 rounds.

Frightful Presence (Ex): The dragon can unsettle foes with its mere presence whenever it attacks, charges, or flies overhead. Creatures with fewer than 31 Hit Dice (except for other dragons) within 270 feet of the dragon must succeed at a Will save (DC 32) to avoid this fear effect, and remain immune to that dragon's frightful presence for one day. On a failure, creatures with 4 or fewer HD become panicked for 4d6 rounds and those with 5 or more HD become shaken for 4d6 rounds.

Spells: Knows and casts arcane spells as a sorcerer of level 13, gaining bonus spells for a high Charisma score. Can also cast cleric spells and those from the Air, Good, Law, and Sun domains as arcane spells.

Spell-Like Abilities: 3/day-polymorph self, fog cloud, control winds; 2/day-feather fall. A silver dragon's polymorph self works just like the spell, except that each use allows only one change, which lasts until the dragon assumes another form or reverts to its own (which does not count as a use of this ability). These abilities are as the spells cast by a 13 level sorcerer (save DC 17 + spell level).

Immunities (Ex): All dragons are immune to sleep and paralysis effects. All silver dragons are also immune to cold and acid.

Cloudwalking (Su): The dragon can tread on clouds or fog as though on solid ground. The ability functions continuously but can be negated or resumed at will.

Blindsight (Ex): Can ascertain creatures by nonvisual means (mostly hearing and scent, but also by noticing vibration and other environmental clues) with a range of 270 feet.

Keen Senses (Ex): Sees four times as well a human in low-light conditions and twice as well in normal light. It also has darkvision with a range of 900 feet.