Hello Stardock again

My second post for the day , I came back yesterday for the 1.2 patch after leaving since the 1.1 version of the game and there is a game bonus that I still can't understand : the random guardian on city level up.

I was playing with the empire, not tried yet with the good guys  . My army was composed of a weak channeler (good in intelligence but with no spells and just the pointed stick), janusk almost naked and a peasant, my city turns level 2. Still that random guardian feature...

I choose it and then something like 5-6 spiders appeared in my city. I had something like 4-10 citizens (didn't look) it's not even realistic "A family of spiders have been impressed by your hut and your workshop and wanted to join your cause" , which at this step of the game are really overpowered, and completely unbalance with X% of "Tech Knowledge, Arcane Knowledge, Gildar Production"

And a subsidiary question, I never understood if the X% between each level of a city are cumulative or if it replace the previous %.

Thank you again for all the good work