Returned After 4 Years, Don't Understand Anything.

Where to begin?

Left playing about 4 years ago, a couple weeks after Lor'tac expansion came out. Got into the game again this week and oh boy, every thing has changed.

I don't understand gem crafting anymore. Why do they have to attach it to a questline? I have legacy higher grade gems, but now I can't craft of the same tier. What happened to the simple and good Workbench? Do I have to use a "schematic" every time?

My whole Legendary and Unique sets are bricked. The hell happened to my last Cloak quest?!

What's all these "cores"? What with the shake up of prices?

And the biggest *** of all...the heck happened to DK?? DK feels very underpowered.

 

Your DK is underpowered, obviously, because you stopped playing during 4 years. DK is the best class of the game.
Just read in this forum the patchnotes section to answer your questions, you can't expect that in 4 years game doesn't evolve and change.

 

Because they attached almost all the crafting recipes to quests.

Seriously, it's not hard at all to get the recipes you will critically need, like the gem crafting recipes.

What happened to every single thing that you don't understand yet because you've just came back after a looooong break?

You need a schematic for every recipe, yes. You don't have to use it every time you do a craft... that would make no sense. One time and you can craft as much as you want.

Not sure what you mean... but the old items don't work anymore. My advice is to change your equipment to random items you find, if you want you can keep some old uniques in your locker as a token of the old times or whatever.

Those quests were removed and the old cloaks were discontinued. Again, you can keep your cloak just for the sake of it, but you should get a new cloak asap and equip it (can be a 25lvl cloak from regular world Khalys).

Check this wiki article. It's not up-to-date with the latest changes in the core system, but it explains all the core crafting methods (there are three) and that's all you need for now, you'll understand the rest yourself.

The whole economy was changed. Drops were changed, prices were changed.

See above post. Your character is incredibly weak (probably with out-of-date legacy equipment), maybe weaker than the average levelling toon now...

Patchnotes are quite messy, and seriously it'd be too hard to read patchnotes for about 60 updates all at once and keep track of everything you need, to find everything you need.