Undead Nation is a little unique that it gives you 3 ways of making your survivors more powerful – excluding badges.
From the title, you would have guessed, I am referring to Level up, Grade up and ascend.
TLDR, Level up gives you about 5% bonus to stats, while ascend and Grade up gives you 10%. These bonus is all to base.
In simple maths, if someone has 1000 hp, each level up will add 50, each grade or ascend will give you an extra 100 hp. The bonus is additive and multiplicative.
In plain English, let’s say you level up someone 2 levels and grade up by 1. – the bonus is not base x 5% x 5% x 10%, but rather base + 5% + 5% + 10%. And they said you don’t use maths…
Next thing to keep in mind, is that just like any other game, the amount of resource needed from one level to the next gets higher and higer. Why this matters, is because of the law of diminishing return – the amount of bonus you get from each boost is flat, but the amount needed to get the boost gets higher.
As a final note, use these numbers as a reference to your pick for the badges and skins. What a +1 level from a skin means for 600 gold means what? and so on.
Happy hunting.