Throshh

Well, the drop rate for gear with runes/sigils is absurdly low, so you're still going to need a great deal of luck.

The recipe is simple and applies to several things. You put four items of the same general type (rune, sigil, dye, or minipet) and level (minor/common, major/uncommon, etc.) in the MF and you get back one, with a chance it will be the next higher level. It may work with items other than the ones I listed, but I know it works with those four. You don't need any stones, scrolls, crystals, wine, or other junk, just the items themselves.

So, for example, you take four random minor runes -- say a minor Hoelbrak,  Melandru, Eagle, and Grenth -- and put them in the MF. You get back one random rune which will usually be a minor but has a small chance of being a major. The four minor runes can be anything, and they do not all need to be different, so you could throw in four minor Eagle, for example, or two Eagle and two Dwayna, or whatever you have handy that you don't plan to use. If you use major runes instead, you have a small chance of getting back a random superior.

I actually get enough junk runes and sigils from salvage that I do the MF trick once in a while just to clear inventory, after carefully checking the TP to make sure I'm not gambling with anything that has a decent profit. A couple of times I've gotten lucky and gotten something I either wanted myself or could sell on the TP for a nice profit, like a Superior Luck.

Many runes can't be crafted, but all can be found on loot drops in open-world PvE and all can be produced by the Mystic Forge. Those are the sources of the non-craftable runes you see on the TP. (Note that the MF recipes for runes and sigils give random results, so there is no way to be sure of getting the type you want. It's a gamble.)