The very minimum.
On the positive side you may indeed get some stability. Note that I said some stability. "Some" is an important key word here. So is "stability", actually.
I'm taking levecirateam, which now constitutes as an anticonvulsant, and lacosamide, which is a different anticonvulsant. Both, however, started as antidepressants. This is the history of most epilepsy medicines - some guy tries to make money out of antidepressants seeing as antidepressants would be needed for as long as humans exist. I've googled "antidepressants for dogs" as a joke and was surprised to discover it is indeed a thing that exists. And so, our guy attempts to make an antidepressant, fails, but notices it works acceptably as an anticonvulsant, so he rebrands his product.
I am indeed somewhat stable emotionally most of the time.
This particular duo made crying impossible for me, which is a bad thing. Crying is a form of release, which holds more importance than you'd believe. The whole "boys don't cry" movement needs some beating.
Second, the prime reason I'm less depressed is because I'm a zombie. Zombies don't get depressed as far as I know, but then again, zombies don't feel anything either.
Now, the reason epilepsy meds fail as antidepressants, I think, is because I'm not always a zombie, only about ⅓ of the time. I do "feel", so to speak.
Whether or not zombieness is good is up to debate.
Much like ctb being a solution to stop pain in all forms, it also stops everything else, including pleasure and happiness.
Of course, the zombie side effect is not a promise, there's always the "uncle jebedaia" who turned his life upside down and is now the happiest motherfucker on earth.
It's not that antidepressants made uncle jebedaia happy, it's that the pills made uncle jebedaia zombie enough to numb the pain, but then uncle jebedaia wrestled the zombie to do his bidding.