Shamash is pretty fun to have. She's the first hime you could call an actual tank. Has a highly effective taunt ability with 5t effect, which also applies intercept+energy drain for 3t, with a 6t cooldown. Has a similar ability as Thor which gets stronger the lower her hp is & heals back 1.5k & as 3rd ability she boosts that even more with pride buff & 50% healing limit break. Now, that's a tank. That said, her real use is pretty niche. She doesn't bring any debuff or buff to the team and doesn't save you from AoE hits & light usually doesn't have issues with surviving, anyway. I could imagine her being useful in a no debuff environment, but that's about it.
Karma is.. RNG debuff. Carries lots of useful debuffs, but low accuracy. And by low accuracy, I mean real low accuracy. You will probably see 1 or 2 land.
And finally Durga is.. random. I have no other words. But either way, I can't imagine her being useful in any case.