The Reversed Dead

What would happen if we were to reverse and play the role of the numerous monster generators in 'Vampire Survivors'?

A magician survived the battle, but he is still in crisis - a hostile undead mage is summoning his undead army to launch a final attack. Can he survive? No, what we should be concerned about is: will he be defeated by us?

English is not my native language, so I apologize for any language issues.