Portal Defense Chapter 3-18 Campaign Strategy

To complete Chapter 3-18 in the Portal Defense campaign, allocate your gold strictly toward high-damage offensive towers positioned at central track bends rather than relying on speed-reduction control strategies. Waves in this stage feature fast-moving enemies across all elements that bypass slow-based lane control. Maximizing raw damage output and overlapping firing zones is the most reliable way to clear incoming units before they reach your portal.

Strategic Tower Placement for High DPS

Position your primary damage-dealing towers along the inside bends of serpentine or zigzag track paths. Because slowing mechanics cannot be relied upon to hold fast units in place, maximizing geometric coverage across the lane ensures enemies remain under continuous fire as they navigate turns.

Follow these placement principles to maintain maximum damage output:

• Focus Fire Clusters: Position high-damage towers within overlapping range radii so multiple units concentrate fire on the lead enemy simultaneously.
• Interior Bends: Build your strongest offensive towers on the inside turns of the track layout to maximize the total time targets stay within firing range.
• Offensive Synergy: Replace dedicated support or crowd-control towers with high-burst elemental towers to maintain consistent lane DPS.

Gold Management and Upgrade Priorities

Managing your economy efficiently is critical to keeping pace with incoming waves. Wasting gold on status-effect towers reduces the funds available for essential tier upgrades on your main damage dealers.

• Audit Existing Builds: Inspect your active towers between waves and sell low-tier units that focus on speed reduction rather than raw damage.
• Target Elemental Weaknesses: Match your tower upgrades to the elemental vulnerabilities displayed by incoming wave compositions.
• Upgrade Between Waves: Perform damage upgrades during the quiet period between waves so your towers are fully powered before high-speed enemies enter the lane.