Anyway diamonds, rubies, or cards would be welcoming. Even like 1 diamond per level would encourage more play and longevity. Longevity. Longevity. On the same note though thought it would be interesting to bring up monthly subscriptions again. $5 per month and every day you can log in and under rewards you can collect your daily subscription reward after 10 games. The reward could be something like:
1 diamond, 500 gold, and 100 rubies or
This would get free players to put some skin in the game and would increase playing volume amongst free or newer players who decide to do this. Even pay players would do this on top of their normal spending.
You could also offer a one time "investment" buy-in. This would be a new player deal and hopefully could apply to old players too. A one time deal. You pay $20 once and after 1500 games you are rewarded with a random epic. Essentially you are offering a first epic deal for each player it at a cost that says "hey if you really like this game and want to play it a lot then we're gonna give you this one time reward at a discount". It's approximately half off and randomized. Investment is used by some other games too to encourage players who like a game to put money down early and stick with the game rather than deleting it Five days later. Of course I don't see many players with one epic. Most with one go on to buy three or four more.
Other rewards could be spending milestones. Such as running tally of what you spent and milestones of say 1000 rubies at $20, 5000 rubies at $100, or something of the sort.
Again, as said before. One legend rewarded at level 60. If you've played 5000 games even as a free player you e contributed to the success of this game.
New pack with special bonus offer. I suggest this as either an alternative to your lucky draw packs or something that can be added as a new pack altogether. lets call this pack "lucky buyers pack" of course that is just a name holder. So here's what this pack is. The cost of the pack is 2500 gold and 1 diamond. It is like lucky stars and gives mostly silver and gold cards. However it has slightly better chance of diamond and legends and a rare chance for an epic cards. For the cost of one extra diamond you are given slightly better odds on legend cards and rare chance at epic card. This of course brings back the old card pack that had rare epic chance but puts a diamond investment into it. The complaint about that pack though was really focused on the fact that it cost a WHOPPINg 10,000 gold and the miss rate was high giving the impression of a rip off. Below is another suggestion that avoids the ripoff feeling allyogether.
Another alternative is to discard the above idea and to just modify lucky stars as such. Everything stays the same however now there is a rare chance of an epic being drawn added. However if you get this epic you are immediately given the chance to purchase it for $19.99. If not oh well you don't get it. The odds can be rare enough that this is not a common thing so as not to mess with your current structure but meant as a lucky lotto reward for the free player as they are given a Chance to become a pay player and get an expensive card more than half off price. A discount reward for their "luck of the draw." They are not out massive amounts of gold really the only thing they are out is a missed opportunity. And if they decide to buy bc of their lucky discount then ecb wins as well.
One problem I see with your current draw system is that it is hit or miss. Some draw costs costs 40 or even 225 diamonds and yet chance to not even get a legend card. Someone who had played free for two months gets a miss=quits the game. This type of pack has some nasty consequences. Of course there is always the flip side where the gambler gets a lucky epic and their efforts pay off.
Anyway just some suggestions to focus on player loyalty.