User blog comment:Visually/Don't do "Summer's Over Update" before claim your mastery rewards./@comment-109.80.17.101-20151014125318/@comment-26536836-20151017114408

Oh, that case, I don't think it is good idea to upgrade Biome. Because Biome's max out price is so expensive. Of course, you can get some free upgrades from mastery rewards.

You should check out the Lykan's upgrade page to see how many cards and cost of max out and pro-ing. http://asphalt.wikia.com/wiki/W_Motors_Lykan_HyperSport%5CUpgrades

I think you should get the Silver Lightning for farming because it's much cheaper to max out (than Biome) and Season 9 race can finish within a minute and 4.7 to 4.8k credits.

Mastery challenge's farming isn't good because pro-ing required many cards and pro-ing credits is quite expensive. So Season 9's farming is still good.