Dryer Straits

Waves 1-10: Start with fully upgraded Gun Towers at the trench edge. Block the top entrance to force runners under the lower bridge. Block three tiles right of the closest vertical trench bridge to direct northern runners up the map. Add more Gun Towers in an 'L-shape' for support.

Waves 11-20: Introduce a Spark Tower near the wooden bridge to hit helicopters and both runner paths. Upgrade it to level three. Place a second Spark Tower at the southern trench entrance. Sell the level three Spark Tower and replace it with a Plasma Tower. Swap the Gun Tower facing the trench bridge with a Slow Tower (Polymorph, Oil, or Ice) and upgrade to level three.

Waves 21-30: Upgrade existing Spark Towers to level three. Place another Spark Tower near the southern entrance's wooden bridge. Swap the Gun Tower right of the Plasma Tower with a Spark Tower. Upgrade both Spark and Plasma Towers to level two.

Waves 31-40: Use your maxed Airstrike on Momma Tanks in round 30. Place a Tesla Tower in the gap between the top Gun Tower and Plasma Tower, upgrading it to level three for helicopters.

Waves 41-50: Replace the Gun Tower facing the top northern entrance with a maxed Flamethrower Tower. Replace the Gun Tower by the northern entrance fence with a fully upgraded Spark Tower. Replace the southernmost Spark Tower with a Plasma Tower, aligning it with the one above. Ensure the top Plasma Tower is level three and the new one is level two.

Waves 51-60: Extend the maze in the north-west corner with a Slow Tower and four to five Gun Towers to its right. Upgrade the three southern Gun Towers. Place a Flamethrower Tower underneath an existing one and upgrade it. Place a third Flamethrower Tower beside the other two and upgrade all three to level three.

Waves 61-70: Swap the remaining Gun Tower below the southern Slow Tower with a fully upgraded Flamethrower Tower. Replace the Gun Tower above the right-hand Spark Tower with a max-level Tesla Tower, and place another Flamethrower beside it.