Tips for the Front Lawn Scenario
Barricade the left side off with 4 barricades, then spam the right bridge with giant flippers and a war tower with 2 archer guardian camps on top, this was round 1-2.
The rest of the rounds I just made more archers on the right side balcony, a giant barrel bomb next to the portal so I can hop back in case any runners get through, and once the boss shows upon the final wave I froze him with the freezing bracelet, and just head shot him until he died.
Also had archers in the very front balcony to help.
Note: If you put the guardian archers on the front, just make sure you put them in the back near the stairs so the bomber archers can’t reach them. I also had fire arrows equipped on them, since I also failed a few times.