Taking of the Necropolis [COMPLETE EDITION]

Regarding the tower – I’d like to see how it works. And does a gremlin separate as a single unit, or is it lost from the main stack?

A gremlin separates as a single unit, and you need two of them (one survives).
Gargoyles are a more useful unit, so they are always in short supply at the beginning, and you need to conserve them.
https://www.youtube.com/watch?v=IRGBsvUIYfg

UPD1: By the way, you can kill zombies without any contact at all. You just need to take about 65 gremlins in the stack, not 80, so that the damage doesn't just go to waste on dead bodies, and that part of the damage can be redirected to the zombies.