Portal

Portals are a handy tower that is placed on the track, and then teleports any creeps that walk into it or fly over it back to the start. It cannot affect the same enemy more than once. They require certain Laboratory upgrades to upgrade.

Base Stats
Special: Teleports enemies back to the start. Teleports the same enemy up to one time.

Cost: 250

Upgrade 1
Special: Teleports enemies back to the start. Teleports the same enemy up to two times.

Cost: 250

Upgrade 2
Special: Teleports enemies back to the start. Teleports the same enemy up to three times.

Cost: 250

Upgrade 3 Path 1
Damage: 100

Special: Teleports enemies back to the start and damages them at the same time. Teleports the same enemy up to three times.

Cost: 500

Upgrade 4 Path 1
Damage: 200

Special: Teleports enemies back to the start and damages them at the same time. Teleports the same enemy up to three times.

Cost: 500

Upgrade 3 Path 2
Special: Teleports enemies back to the start. Teleports the same enemy up to four times. Every three waves, it makes 5-10 mini-portals that teleport 15 enemies each before disappearing. Mini-portals can teleport the same enemy however many times it wants to, but each time it teleports an enemy, even if it's one it already teleported, it loses a use, and disappears at 15 uses.

Cost: 1500

Upgrade 4 Path 3
Special: Teleports enemies back to the start. Teleports the same enemy up to five times. Every wave, it makes 10-20 mini-portals that teleport 30 enemies each before disappearing. Mini-portals can teleport the same enemy however many times it wants to, but each time it teleports an enemy, even if it's one it already teleported, it loses a use, and disappears at 30 uses.

Cost: 4500

Weaknesses

 * Ninja Elitist