Putting all the clues and such that I had in the puzzle here(partially for easy copy/paste in the thread later once its over), and for anyone who wants to see what clues they may have missed while solving this. Spoiler text is either off topic or just saving you from decrypting the message(the random number and uppercases are red herrings to make a brute force decrypt even harder).

Solution: Use Enigma in the cipher as the key to get oxZSPHV out of the decrypted message(in the spoiler) YouCanfindAcCesstoTheGiveaWayTrainAtTheFo1lowinglocatioNoxZSPHVnowgoDestroyMephistosSoulstoneAlready
which is used on the redirct link used by SG for comments(found on the permalink button for comments https://www.steamgifts.com/go/comment/oxZSPHV, the 5 digit code for the train station was found there and the SGtools link was found at the train station.

Cipher used: Beaufort Cipher, this is a variant of Vigenere cipher, initially this was left to trial and error but I eventually named it in hints as a number of people were getting caught up on this step, the main puzzle was intended to be finding the key: Enigma, not getting stuck on the cipher step.

How to reach the solution: I laid a variety of clues leading you to a diablo 2 wiki or similar, eventually to make it to the pages for runes, how to use them and potentially runewords. The answer is also found just on the pages for the Jah Rune and Ber rune if you found yourself on their pages from image searching my drawing by looking at what runewords use them, there is only one that uses both in a 3 socket runeword in body armours.

My crude MS paint drawings are of the Jah Rune and Ber Rune, I couldn't manage to get the Ber rune image searchable(maybe findable with google lens), but if you isolated the image search to just the first rune you would have gotten results for the Jah rune(don't worry... this only took like 10 attempts at making it in paint to make it actually get results), while all the results are for products(not linking/using images as I don't want to check SG rules regarding them), if you looked at the recommended/more products from the sellers they all also had Enigma(this is one of few ways(with the fastest being enough game knowledge to just know the answer) you would have gotten the key, skipping figuring out what the third rune is completely and what to do with it!), if you didn't you at least knew the name of the first rune, the Jah rune which could lead you to the answer on its own.

ALL the poll options are modified text(words changed to potato) from the Act 1 NPCs in the rogue encampment of Diablo 2, 2 of them are searchable just by removing the word potato, some of the others if you could figure out what the actual word I replaced with potato was became searchable. This is to help point you to diablo 2 related sources.

if you had opened imgur you would have found the description(part of why the puzzle solving guide was linked at the start!): Socket into the 3os MP for the Paladin please, googling 3os MP would have led to a bunch of trade forum results for 3 open socket mage plates(3os MP is used in game due to limited text length for game names/descriptions), this is also telling you to put the runes in it. I included the Paladin as it is one of the more popular(and absolutely OP) classes in the game, to try and lead people to the correct runeword as hammerdins become one of the safest magic finding characters in the game when they can teleport(previously one of the best... but sunder charms and terror zones have changed things(they are still pretty good)). Combining that with the puzzle description noting that the runes make the key hopefully didn't lead to many people trying Ith or JahIthBer as the cipher key.

I also may have hidden the url for the 7 digit code here for those snooping around with inspect element, there was no hints pointing to inspect here specifically, but its a general puzzle tip for hidden things!. The way to use SG 7 digit codes was otherwise findable within a few of the other puzzles that had ended(double trouble by twchiu(they closed their post since... but a different one with a way to use 7 digit ended before they closed it)... and ended during(the true/false one by DogOnSG), I think there was others to but I can't remember every puzzle on SG(I did make sure there was always one visible with the solution).

apologies if I missed something in explaining it(I suck at describing and explaining things), Cryptii is recommended on mouse hover of the image as you can input the message for decoding and bouncing between ciphers without losing it(its also just a good tool in general to have bookmarked for SG puzzles). Its recommendation is basically invalidated by naming the cipher in the hints.

Great game, hope whoever wins it enjoys it, it's very fun to 100%

thank you