Frost giants seem to get the most play - is it the viking thing? Strong elemental flavoring + the viking thing probably does it. Let's take a look at a few more frost giant-related adventures.
Dungeon magazine #20, for AD&D, levels 3-5. This viking-themed jaunt starts with the PCs couriering a shipment of black lotus. Yes, really! The journey may feature encounters with mundane animals, a hag, and some half-ogres with mastodons (love it).
When the heroes get to the village to make their delivery, the real nonsense starts. You deliver the black lotus to the chieftain, and during the evening feast, he tells the tale of the frost giant king Mok-Turoknin and the giant-slayer Rognvald. It's a long story, and at the end of it, the candles blow out and the ghost of Mok-Turoknin bursts into the meadhall, chops the chieftain in twain with his ghost-axe, cackles and fades out. Well, there's a start to things! Maybe start this one at the delivery!
How to end the ongoing curse? The answer is provided by NPCs: go to the frost giant's tomb, find Rognvald's giant-slaying sword, and get back here before the next full moon, when Mok-Turoknin's ghost is sure to strike again. This is all fine stuff but I wish it weren't a mid-game expository dump and instead the PCs could find it out on their own, or intuit it. So it's off into the frozen giant-lands, where mammoths and devil-dogs and quaggoths dwell. (Three cheers for quaggoths)
We're told that recent seismic activity has shaken the frost giant's hall, causing a) new monsters to be able to get in, and b) Mok-Turoknin's axe to fall from the hand of his frozen corpse, thus stirring the ghost, causing the chieftain's nightmares, and so forth. Earthquakes in D&D have a lot to answer for, they do this stuff all the time.
The Hall has some neat stuff in it, but man this adventure is wordy. Sign of the times I guess. It has the standard arctic foes - ice lizards, white pudding, snow-variant beetles and the like, and of course the inevitable remorhaz. It's a frost giant's hall, but there aren't any giants here - the place is long-abandoned and in ruin. The tomb of Mok-Turoknin is short but does feature barbarian skeletons (that's fun to say), and it's where you might find the giant-slaying sword Thorgrim, which can cause its wielder to fly into a berserk rage in the presence of giants (so that'll be a surprise for the PC that walks away with it, since there are no actual giants here). The PCs can either put Mok-Turoknin to rest (avoiding combat), or screw it up and have to fight his apparition (not an advisable course).
This adventure has potential. I think it benefits from actually doing the overland horrible snow-trudging portion, really punch the desolation angle. Tonally it would fit pretty nicely with Doom of the Savage Kings.
Frozen Castle is for 11th-level 5e characters, and was released as expansion content for Tyranny of Dragons. Don't let that fool you, though - believe the cover art, this is a giant adventure. It involves chasing after a crashed flying castle and potentially getting it running again, and while its designed to be a certain castle from Tyranny, you could run this by itself with a suitable motivation.
The map gives us an orc tribe loyal to the frost giants, a dwarven settlement, and the meadhall of Brunvild, frost giant chieftain. There's also the cloud giant Blagothkus, a white dragon, some werebears, a colony of yeti... plenty of stuff going on, some of it environmental, and a lot of it factional - stuff you could really leverage as a PC.
The issue is that since Frozen Castle is meant as extra content for Hoard of the Dragon Queen, it doesn't have the maps of the cloud castle or the glacier. So on its own, it's less useful as an adventure in itself; however, if you're looking for some bits & pieces to drop on a corner of your tundra map, this supplement has something for you.
A GIANT RANSOM
A Giant Ransom was released in chunks during the 3e era on the WotC website; it's for 11th-level characters. The Duke's cargo train, moving belongings to his new keep, was waylaid by giants. The most important thing stolen was a golden lion statue; in order to avoid conflict, the Duke offers the giants a ransom to return the statue, and they agree. The PCs are called in to provide security for the exchange. Unfortunately, the white dragon Whildenstrank knows what's going on, and is prepping to steal the statue...
The PCs are within sight of the frost giants as the dragon swoops down and attacks; by the time they get to the site of the battle, it's all over. The surviving giants suspect the dragon was working for the Duke, and the PCs head off to follow the dragon. Along the way they encounter Velg, a frost giant ranger and dragon-hunter, who can either be fought or talked to for information.
Later, the PCs are attacked by arctic landsharks bursting up from under the ice and snow (this is for sure the most original encounter in the adventure). When that battle ends, the ice beneath the PCs crumbles and collapses (no roll here, tickets please). PCs can dig themselves out, head through some ice caverns, engage with winter wolves and a remorhaz...and then fight the dragon.
There's not much here that you wouldn't have put together yourself. The idea of a white dragon dominating a pack of winter wolves into being his minions is neat.
Dungeon magazine #6, for AD&D levels 4-7. A snowy town has placed a sizeable bounty on a white dragon - go get 'em. The rumors the PCs get make the dragon out to be worse than it actually is - would be interesting to see that play out at the table.
The journey to the dragon's den has a wilderness encounter table and talks about arctic weather conditions. That encounter table has some frost giants on it, as well as winter wolves, remorhaz, ice toads...you know the drill. This adventure will work better if those frost giants are a known quantity and potentially have intel on the dragon.
The lair itself is small... the gimmick here is that atop the pile of treasure is a dead, older dragon, preserved by the cold and the ministrations of the current dragon occupant, who awaits to leap down on invaders. Also, that treasure pile is fake. Also, the young dragon was previously subdued and in captivity, so attempts to subdue it make it go berserk instead. That's a lot of screw-yous in a row, I think the results are going to vary by table. There is real treasure here - some monetary (but maybe not enough to stave off anger after the bait-and-switch), and some magical (good stuff, but hidden). One thing the adventure doesn't address - but which your PCs will ask about - is whether the preserved dead dragon yields enough scales and hide to do KEWL DRAGONY ARMOR STUFF with. They will ask. They should ask. And in that case, the real treasure from this encounter is two dragon corpses.
This is an okay setup, it's definitely from the "we've all fought dragons a dozen times and want something with a twist" era. I think this would work far better plopped on a map than as a "here's what we're doing tonight" adventure.