How do defensive waves work?

So I got 3 waves unlocked currently, with 28 sec distance between them. I’d assume there would be 3 groups of units 28 seconds apart, that start from my gate and go towards the attacking enemy.

However, when I test my defense, there are 2 groups immediately on the path, at different places, a third one starting at the gate a few seconds into the offense and groups just keep spawning till the time runs out.

And now I’m confused.

Hello Chee7ah,

You can have a look at the FAQ for more information about the game mechanics:

 

Okay, that clears it up. But this way upgrading Guard of Thanatos makes my defense actually weaker…

So I had 3 waves with 10 moral points each, which apparently spawn in a loop, making first waves more important. Cool, every wave 10 moral points. Now I just finished upgrading, got the 4th wave, with 4 moral points being put into the first position… The most important wave went from 10 moral points to 4 after the upgrade. So now I have to upgrade that wave quickly to 10 in order to fix this new weakness and at that point the value I got from upgrading Thanatos is a meager 1 sec between the waves (since the waves are on a loop, having 4 instead of 3 doesn’t really mean a thing). So I spent a lot of money, and only got a 1 sec difference… Not a good deal at all.

To be fair, after this point I can go ahead and upgrade my waves to have more moral points, which is valuable, but having more waves just makes it more expensive without adding value to it.