the final upgrade costs this much if you only use numerical: 3,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000
I like that you can mix units on each tower. If you make a second one it would be cool if the tower would get a bonus aura for the combination. For instance, a frost unit plus archer could make frost arrows.
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