Age of Origins Level 20 Normal 3-Star Guide

To earn three stars on Tower Defense Level 20 Normal in Age of Origins, you must prevent all zombies from reaching your base and finish the stage with zero base damage. The stage features split spawn paths that funnel into a single lane, requiring you to concentrate your defenses around the central merger rather than building weak towers near the spawn portals.

3-Star Requirements and Key Targets

A single leaked runner will ruin a three-star attempt. Because Level 20 alternates between dense swarms of fast runners and heavily armored mutant targets, your defense must balance area-of-effect splash damage with focused single-target fire.

Initial Choke-Point Setup and Wave 1–3 Upgrades

Do not place towers right outside the monster entry gates. Spreading your starting energy across both outer lanes reduces your total damage output and allows enemies to exit firing ranges before dying.

1. Place your initial slow field: Build an Electro-Magnetic tower at the corner of the primary intersection where both enemy paths converge. Keep this tower at Level 1 during the opening waves, as its base slow percentage is sufficient for early movement speeds.
2. Build immediate damage support: Place one Machine Gun tower and one Rocket Launcher on plots directly adjacent to the Electro-Magnetic tower. The Rocket Launcher hits bunched enemies with splash damage while the Machine Gun eliminates lead runners.
3. Upgrade the Machine Gun to Level 2: After clearing Wave 1, invest your earned energy into upgrading the Machine Gun to increase single-target burst against leaking units.
4. Upgrade the Rocket Launcher to Level 2: Upgrade your Rocket Launcher before the first armored waves appear to ensure heavy group damage against clustered swarms.

Prioritizing Level 2 upgrades on existing choke-point structures provides significantly higher firing rates and damage multipliers than filling open tiles with Level 1 buildings.

Mid-Wave Positioning: Laser Towers and Chained Slows

As mid-stage waves begin introducing shielded enemies and denser hordes, kinetic towers alone will struggle to clear high-health targets before they pass through your kill zone.

• Add a Laser tower behind the intersection: Place a Laser tower where its firing arc covers the longest straight stretch of track leaving the junction. Lasers deal escalating continuous damage, which is necessary for melting large mutant health pools.
• Construct a second Electro-Magnetic tower: Place another slow tower further down the track to establish chained crowd control. When infected leave the first slow field, they enter the second field while remaining in range of your upgraded Rocket Launcher and Laser.

Late-Game Execution and Boss Waves

The final waves deploy high-health bosses flanked by fast-moving escorts intended to distract your towers.

1. Max out core damage towers: Upgrade your primary Machine Gun and Laser towers to their highest affordable tiers before the final wave starts.
2. Deploy a secondary Rocket Launcher: If you have surplus energy, build an additional Rocket Launcher near the rear of the choke point to mop up low-health stragglers.
3. Focus fire on escorts: If manual targeting is available, target fast escorts first to clear them from the lane. This allows your Laser tower to maintain an uninterrupted lock on the main boss.
4. Recycle ineffective towers: If an early tower placed near an outer lane no longer contributes damage, sell it to reclaim energy and reinvest those funds into defenses guarding your exit.

Mistakes That Ruin 3-Star Attempts

• Spamming Level 1 towers: Filling the map with un-upgraded towers starves your primary choke point of the energy required for high-tier upgrades.
• Building without slow coverage: Placing pure damage towers without overlapping Electro-Magnetic fields allows fast enemies to sprint past during attack cooldowns.
• Ignoring single-target beam damage: Relying purely on Rocket Launchers leaves your defense vulnerable to beefy mini-bosses that survive splash damage.