The following steps will show you how to beat the final boss without taking any damage (Therefore, You gain 2 achievements)
How to prepare:

I highly recommend having at least 6 cool down timers. This way you can use slow time and nuke together to wipe out the totems when they spawn minions. You need to eleminate the totems as soon as they spawn. Otherwise, the minions gain speed and rush into your base. The cool down skill also buys you some valuable few seconds to figure out what you need to do.
I highly recommend at least 3 heart or health items. This way you can recover lost health if a few zombies make it to your base.
The robotic creature is very powerful also because it eleminates all land enemies. This way you can focus on air enemy units and manage the situation.