It is very hard to have this info as you can't find this on tutorial or in forums. If you set your team up and just need power to reach upper leagues, renting common level 10 cards will give you something like 7500 power whereas regular legendary will give you between 1000-3000 and gold foil common and rare cards will give between 500 and 6000. And the price you will pay will be much less with the level 10 common cards if you can be patient in the market. See the picture in this post, I get 7953 power with a level 10 common fire monster. It would be very expensive to have the same power with gold power or legendary cards. I think this info is essential for new players and should be added to tutorial.
