At any combo master, when exchanging runes, you have to use at least 3 runes to get a 1/2 way decent chance of getting a rune you actually want. That's a major bummer.
But don't fret, because I'm going to tell you how to make only 2 of your runes giveyou the result of 3!
First thing you need to do is quick-save your game [F8] (preferably right by the Combo Master) Then do a rune exchange using only 2 runes. Chances are you will get a rune that is no good. (if it IS one you can use, then take it, no need to exploit!)
Pick up that no-good rune and stick it in one of the exchange slots (do NOT put it into your inventory or close out the exchange window, the glitch will not work)
After you have put the no-good run into the exchange slot do a quick-load [F9] (remember, do this while still in the exchange window!) After the game reloads click on the Combo Master again and go into the exchange window. Surprise! That no-good rune is still there and the 2 runes you wasted to get it are back in your inventory! You can't use it or put it in your inventory or anything. You may pick it up, but it won't do you any good. So, with that no-good rune still in the slot, put up 2 runes from your inventory and click the exchange button.
Whamo! You get a random rune from YOUR class. If you don't like that rune, just stick it in the exchange slot and repeat the process.
Submitted by The Dungeon Master