Nymphs being unwinnable in slots is just insane.
I haven't won a single one yet and I use the Oracle every day. My friend who started to play much later already has four on his main account and another three on his secondary.
No matter how hard it is to obtain a card it should be possible if the player spends enough effort. Having to WAIT a year or more just to win the one you actually need is stupid, and I didn't even mention what if you need more than one in the same in the deck? Besides if you aren't lucky, with an 1:144 chance, you might as well forget about starting to "collect" them. You might not even live long enough to win six of the same nymph...that is if you are still playing the game then...which isn't too likely. 12 of each of them, to also have upgraded an unupgraded ones is...something none of us will live long enough to have.
Having no Nymphs on my 61000 score account while people with 2000 score often have 2-3 of them is just unfair. This is a strategic card game (with a bit too much grinding), and not a lottery game of "who wins a nymph first".
At least none of the nymphs are game-breaking. If a card with the strength of something like hourglass, sundial or phase shield would be Oracle only, that would be the end of the game.