Because heroes increase in cost exponentially as they level up, they cease to be cost-effective extremely quickly. As such, the general rules for purchasing heroes and upgrades is as follows:
- Level up each hero to level 10 and purchase their first upgrade before moving on.
- Only after you have purchased 3-5 more heroes following this progression should you go back and finish buying that hero's upgrades. When exactly you go back and do this depends on how useful the high-level upgrades of that hero are. Midas has extremely useful upgrades, so he should be upgraded as soon as his next upgrade level is affordable.
There are also some notable exceptions to this rule. For example:
- Brittany, The Masked Samurai, The Great Forest Seer, Natalia, Ma Zhu, and Athena all lack upgrades that benefit higher-level heroes. As such, it is unnecessary to strengthen these heroes past level 10 until you start preparing to Ascend.
- Grant and Frostleaf are so expensive that it is actually efficient to level the hero prior to them up past level 10 before moving on. Level Shinatobe up to level 18[verification needed] and Grant to level 25 before buying the next hero.
- Heroes which do not have a +100% upgrade as their first upgrade should be leveled up to level 25 before moving on.