Must Be On Fourth Map (Mall Map) -
First Get The "Chief Technician" And "Letterman" Achievements, Then You Are Able To Make Siege Breakers.
Once Crafted, Use This Barricade To Push Your Way To The Portals.
- 6-8 Of Your Spare Archers Follow Along.
- You Can Even Drag It Backwards To Prevent Big Enemies From Thwacking It As Much While Your Archers Unload
- Your Mechanic Will Fix It After It Takes Damage, But It Can Not Be Under Attack While She Does This.
- "Smart Guy" Can Build A Remote Control Laser Turret Which Will Follow The Barricade, Same As The Archers.
Get Close Enough To Let Your Archers Tear A Portal Down And The Achievement Is Yours.
Be Careful, These Portals Are No Joke, More Often Than Not The First Time You Attack It One, They Spawn Some Mega Slugs To Try To Stop Your Advance.
Good Luck!