10th Anniversary Artifacts: The Anti-virtue dungeons, both Trammel & Fel (Covetous, Deceit, Despise, Destard, Hythloth, Shame, Wrong)
Champion Spawns: These give replicas - plus the chance of the Artifacts above, if one of the champs in an anti-virtue dungeon. Merkatus in the Labyrinth is a quasi-champ spawn that doesn't use an altar, but is a type of progressive spawn that EMs can set up their own versions of for events (which is why it doesn't drop pink scrolls but does have replicas). Champ spawns not in Fel or Ilshenar consist of Serado in Tokuno, the Bedlam Cemetary Underground (not to be confused with the Grizzle peerless or the normal inhabitants - reached through a crypt in the cemetary), and the ones in the Abyss.
Doom: Gauntlet gives arties for killing the room monsters and the Dark Father. Other Arties are stealable.
Peerless: see the Mondain's Legacy and Stygian Abyss lists of these.
Reknowned: sort of like a mini-champ spawn, they are mostly in the abyss (one is in Ilshenar, upgrading a classic area of that facet). Have some special items drop.
There are also a few special items that are rare drops of creatures in overland Ter Mur - the Boura Tail shield, for example, that must be looted.