In this update, I removed the old restriction that prevented you from unlocking multiple skills of the same category in a single run.

You can now combine Shadowball, Novashield, and Firewalk in the same game — and this also applies to ultimate skills. It’s now possible to have Inferno, Stormblast, and Deathdance all at once if you’re lucky.

To keep things balanced, unlocking one skill will slightly reduce the chances of getting another skill when you level up.