no, just two
without anything -> with skulls and spikes. that would be enough.
It's not a base, just a tower.
Oh and btw, I have thought of a base:
The crypt model - from inside the game, the undead barracks building - can u make it ... with 2 upgrades to look like a base ? Just add something ... like some obelisks on the four ends and some skull piles near the ground for tier 2, and something like that rotating spiked thing the slaughterhouse model has in the center for tier 3.
(That's just an idea)
So about the tower - just 2 forms
Thank you.