24 transmog appearances in Ulduar.
Boundless GazeMail Head
Breastplate of the TimelessPlate Chest
Bulwark of AlgalonShield
ConstellusOne-Hand
CosmosHeld In Off-hand
Drape of the MessengerCloth Back
DreambinderTwo-Hand
Fang of OblivionOne-Hand
Gloves of the Endless DarkLeather Hands
Legplates of the Endless VoidPlate Legs
Observer's MantleMail Shoulder
Pharos GlovesCloth Hands
Planewalker TreadsMail Feet
Pulsar GlovesCloth Hands
Sabatons of Lifeless NightPlate Feet
Shoulderplates of the Celestial WatchPlate Shoulder
Skyforge CrossbowRanged
Solar BindingsLeather Wrist
Star-Beaded ClutchLeather Waist
Starfall GirdlePlate Waist
Starlight TreadsCloth Feet
Starshard EdgeOne-Hand
Starwatcher's BindingCloth Waist
Zodiac LeggingsLeather LegsSign in with Battle.net to see which of these appearances and collectibles you already have, and which of your characters can still loot Algalon the Observer this reset.