https://www.amazon.com/Tower-Mage-LitRPG-Isekai-Fantasy-ebook/dp/B0BK6XWH49

Defend Hexen, Gain Levels, Acquire additional Towers
Nobody mentioned how hard being a champion on Loral would be. Rico still would've gone if they did though, because his new family is everything to him. The problem is, the damned Shrezen are coming and each wave brings harder armies to defeat. He wanted, no, he hoped for a brain dead legion of zombie type opponents.
The armies that assail the walls of his little outpost are cunning generals leading resolute troops who only care about one thing: defeating Rico and those he holds dear.
Faced with threats around him, and a changing outlook on life, Rico will rise to the challenge in this second installment.