Eliminate Impossible Arena Spins

[Elbirn]

I was recently grinding silver, and received the following "Rare spin".

Wheel 1: Owls eye, Pulverizer, Owl's eye, Owl's Eye
Wheel 2: SoB, SoB, SoF, SoF
Wheel 3: SoF, SoB, SoF, SoF

Or something along those lines. I cannot recall the exact order, but I took careful attention to note which possibilities occurred on which wheel.

This is also certainly not the first time this has happened to me, and I'm certain it happens to everyone all the time. I don't mean to complain about it. It's not like I can't go get another 4 wins in a row. But it can be a very frustrating outcome to players, especially newer ones, who are trying to grind for rares and find themselves being trolled by the slot system.

[Kamietsu]

Just because those were the ones tha tyou saw show up, doesn't mean that was all of the ones in the spins. You don't get shown every card in the slot spins each time. Sometimes you will just get the same card 4 times without a chance to see any other card in that spin.

[Elbirn]

So if I understand correctly, I interpreted it as wheel one having an entirely different set of possibilities from wheel 2/3, thus making the spin un-winnable. But what actually occurs is that all three wheels have the same possibilities, I just happened to have awful luck and saw nothing in common between 1 and 2/3?

I think an explanation of how the rare spins work would be very helpful. Ex, my confusion here, odds of which cards can be spun where (I'm convinced that certain shards are more common in higher tiers, though I'm probably incredibly wrong), how many possible rares there are per spin, (I'm certain that not every rare is put in the slots in every spin. The odds of winning would be even lower.) etc.

Is there already a thread discussing the mechanics?

[Tirear]

So if I understand correctly, I interpreted it as wheel one having an entirely different set of possibilities from wheel 2/3, thus making the spin un-winnable. But what actually occurs is that all three wheels have the same possibilities, I just happened to have awful luck and saw nothing in common between 1 and 2/3?

I think an explanation of how the rare spins work would be very helpful. Ex, my confusion here, odds of which cards can be spun where (I'm convinced that certain shards are more common in higher tiers, though I'm probably incredibly wrong), how many possible rares there are per spin, (I'm certain that not every rare is put in the slots in every spin. The odds of winning would be even lower.) etc.

Is there already a thread discussing the mechanics?

Xeno explained how it works in his Game coding Q&A thread:

I am not sure if this was asked already but my question is, How are cards picked for the bonus spin? Is it just like regular spins where it picks X amount of cards or is it from all the rares in-game except of cource nymphs/marks. Also from which pool are the cards picked  for the slot change (Where you can change a slot up to 3 times).

Exact same as the regular spins; 4 random rare cards (note that some may be the same). When you respin it picks from those same cards.

[teffy]

Spoiler for table:

0 rares winnable	12,7%
1 rare winnable	52,0%
2 rares winnable	30,8%
3 rares winnable	4,4%
4 rares winnable	~0,06%

And because of the mechanic explained above, the thing you experienced happens in ~13% of all games, that there´s no rare card, which is in all spins slots. Numbers above gained with a java program.

[Tirear]

Spoiler for table:

0 rares winnable	12,7%
1 rare winnable	52,0%
2 rares winnable	30,8%
3 rares winnable	4,4%
4 rares winnable	~0,06%

And because of the mechanic explained above, the thing you experienced happens in ~13% of all games, that there´s no rare card, which is in all spins. Numbers above gained with a java program.

I think you are misunderstanding, there is one pool of four cards, not one for each slot, so the situation you describe is impossible. Some searching has brought up a post from Zanz explaining how the normal slots worked just one month after elements was created:
Link
Note his table at the end shows no outcome where winning is impossible. This mechanic has clearly been changed since that time (particularly the pillar mechanic) but I see no reason to believe that he made such a big change to the core mechanic which has no benefits beyond making it harder to win cards.

[teffy]

Huh?
 I know, that there´s a pool of 4 cards, which is used for all three slots. I read the Q&A - and zanz´s post a long time ago. But why should it be impossible then, that rare 1 is always in slot 1, rare 2 in slot 2, rare 3 in slot 3 and rare 4 not used(only an example).  Or the result in the OP. In the OP, Owl´s Eye, SoB, SoF, Pulverizer are chosen.

It´s a possible result. And if you TRY that with a program, using xenocidius´ explanation, you get a- ~ 13 % chance, that it happens, that there´s no rare in all 3 slots.

Winning is impossible, when the 3 slots have no rare in common, and it´s guaranteed (using the right strategy) , if each slot contains 4 different rares.

Edit: Ah, I think, I see your thought mistake: zanz shows a table  with probabilities,how many different cards are chosen in the first 4 (former 5) cards and the table looks similar.
But my table shows, how many cards are in the intersection of the 3 slots. When there´s none in the intersection, no rare is winnable. And that happened to Elbirn.Totally different table, different meaning.

For the case above:
{Owls eye, Pulverizer, Owl's eye, Owl's Eye } ∩{SoB, SoB, SoF, SoF} ∩{SoF, SoB, SoF, SoF}= ∅

P.S
I meant slots, not spins in my quoted part. "that there´s no rare card, which is in all spinsslots."