Two Step

Two Step is a special mission. The rounds are like normal rounds except that only on odd-numbered rounds you can take a single action.

Actions
You can only take one action. These are the things that count as an action: Example: On round 1, you could buy a single dart monkey, and on round 3, you might upgrade your tower. However, you can also take an action on round 4 if you didn't on round 3, or an action on round 6 if you didn't on 5, and so on.
 * Buying a tower
 * Upgrading a tower once
 * Selling a tower
 * Placing an agent
 * Selling an agent
 * Using a power
 * Using an injection