That is why I think the best way to combat the "unfair" means of play would be through adding a pack you gain from taking part in the tournament that could have a 5% chance to get the card.
1-3 Get card
4-10 Get 3 packs to try for card
11-20 Get 2 packs to try for card
21+ Get 1 pack to try for card
At least then everyone has a chance to get card, and odds are if a person gets a duplicate of said card the exchange rate will only be 600 MGP or 1k and honestly if the people who might take advantage of the point system are that pressed for MGP, I don't know what to say lol.
With that in mind if they MGP you can get for placing 1-3 or even 1st is 140k then another change might be to have the MGP gained be based on points and win rate So maybe something like
15 wins=100% MGP gain and then point value seeing as let's say you can get 2k=140k MGP
So you have a 15/15 win rate and 2k points then you obtain 140k MGP
If you have 50% win rate and 1k points that 1k=70k but then you would have to cut it in half cause of win rate and you would get 35k MGP
The twist here is people might be less willing to do win trades if the incentive of winning and gaining points also gives them more points so say rather than
The MGP you get is based on what you place it's now placed on your win rate and how many points you accumulated during those wins.
Maybe you win 15 times but only get 70 points a win that's 1050, So you would get a little over 70k MGP
In that same sense a person could have 1k point but only half the wins and only obtain 35k MGP
The idea ties more into how willing people are to throw a match if it means they get less MGP sure the card is nice and people could "trade win" and take turns obtaining it and the MGP but if there is a fair chance for everyone to obtain MGP then people could have more fun with it?
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In essence the idea is this the 1-20 Rewards would still exist but instead would be replaced with the following
1-3 Get the card and that's it
4-10 Get 3 packs to try for card
11-20 Get 2 packs to try for card
21+ Get 1 pack to try for card
Then based on your win rate and the amount of points you accumulated you are rewarded with an MGP reward.