From Publisher's website:
A new mini-module by Dungeon Master's Guide author Monte Cookintroduces us to a wily white dragon named Charasta. Drop June's free online adventure, A Frigid Demise, into your new Forgotten Realms campaign in the North of Faerûn, or use it in any setting you like. Dragon encounters are traditionally time consuming and difficult to prepare, so save yourself some time time by picking up this challenging and complex encounter for four 13th-level characters.
Charasta, an old white dragon, has not reached her age by being unprepared or foolish -- she is, in fact, much more intelligent than most white dragons. Her lair is well defended and tailor-made to help her defend herself. Not only that, but when she leaves the caves to hunt, she's taken to using change self to disguise her exact color.
You can insert her small cave system into almost any subterranean adventure -- any time the PCs are exploring an underground area near a river. The dragon uses a new magic item to keep her lair always chilly, so there's no need to use this encounter in an arctic area -- even a tropical area would work (and really surprise the PCs!). Meeting Charasta can be the climax of a longer dungeon-style adventure, or you could run A Frigid Demise all by itself as a dragon-hunt.
Area 3: Hidden Cave (EL 5)
A long shaft rises up out of the water into the ceiling of this cave. The sides of the shaft glisten; jagged shards of wet ice coat every surface.
At the top of the shaft lies a cave coated with ice. The ceiling is thick with particularly large stalactites.
The walls of the shaft are coated with ice, so the Climb DC is 30. Further, a character touching any of the surfaces including the floor, walls, and ceiling in the hidden cave, must make a Reflex save (DC 20) or slip due to the slickness of the ice.
Trap. Unless the PCs locate a hidden stone lever at the bottom of the shaft (DC 30 to do so) and pull it down, the stalactites immediately above the shaft in the cave are rigged to fall when anything passes 20 feet above the surface of the water. Anyone struck by these falling stones while climbing must make an immediate Climb check with a -4 penalty or fall.
Falling Stalactites: CR 5; Falling mass of rocks (10d6); Reflex save halves damage (DC 15); Search (DC 28); Disable Device (DC 24).
Treasure. Within the largest stalactite that remains held fast to the ceiling is a secret compartment (DC 28 to find) that is locked (DC 30 to open -- the key can be found in Area 7). Within this compartment, Charasta keeps a special treasure: a white diamond worth 5,000 gp, which the dragon's mother gave her from her own hoard.
Charasta's Tactics. Charasta can appear here in a smaller form. She does not come here when threatened and, in fact, will teleport away rather than be cornered in the hidden cave.