The previous iteration of the Iron Curtain was a huge success for the Soviets and warranted an upgrade. Now capable of making up to nine vehicles impervious to damage, an increased shield duration and immunity to mind control, the Iron Curtain is a bigger threat than ever.
While Invulnerability also works on structures, for unknown reasons it does not work on infantry and the M.A.D.M.A.N..
In Mental Omega, the Iron Curtain's cooldown is increased from 5 minutes to 6 minutes. Another major change is that it can no longer instantly harm infantry. Nonetheless, it remains as a terrifying superweapon, as it counters the myriad of status effects that could hamper advancing Soviet forces (such as confusion, mind control and firepower/armor/speed debuffs).
Its primary use is for Soviet armored divisions to break through heavily fortified defenses without taking casualties. The invulnerable vehicles would take the brunt of incoming fire, while the remaining Soviet army retaliates without fear of their own demise (as long as the opposing commander does not directly order their units to ignore the invulnerable vehicles). As the Force Shield is now exclusive to the European Alliance in standard circumstances, most factions cannot reliably protect their buildings, encouraging Soviet players to target critical structures. The Iron Curtain can also be used to decimate an enemy battalion. Although enemy forces are likely to retreat when doing so, this opens up an opportunity for the Soviets to push back an enemy offensive when it would have failed without the Iron Curtain.
The most eligible targets for an Iron Curtain activation are monster tanks (main battle tanks are the alternative if monster tanks are not available) due to their reliable damage output. If the enemy forces are too dangerous, invulnerable Terror Drones will surely soften their ranks before the Soviet forces arrive. Even Demolition Trucks (or Bomb Buggies for the Latin Confederation) can be rendered invulnerable, which guarantees destruction of opposing critical structures (e.g. War Factories and tightly packed power plants). Other vehicles should only be targeted if they are worth saving (particularly siege units and MCVs caught in an ambush).
The Iron Curtain can also be used in a base defense situation; its Invulnerability power can be used like a Force Shield to protect vital buildings (especially those that grant Tier 3 access, as they are often key targets). However, since its effective radius is smaller than the Force Shield, a Soviet commander can often only cause 1 building to become invulnerable (unless the buildings are small enough to fit inside the 3x3 area), so deciding which building to save can be crucial. If an attack is surely anticipated, the Iron Curtain should be activated before the base suddenly loses power; otherwise, the Iron Curtain's last resort use would be delayed (indefinitely if the Iron Curtain is destroyed).
Despite its immense potential, the Iron Curtain can be a burden to a Soviet base thanks to its tremendous energy and cost requirement (though Nuclear Reactors quickly resolve this). Additionally, its countdown and activation is visible to all players, so the use of an Iron Curtain is predictable (especially to human players). Lastly, should the base lose power, the Iron Curtain is disabled.
The A.I. will usually use the Iron Curtain to render 2 Borillos/Armadillos invulnerable, so that they are free to scorch buildings until the effect subsides.
In the campaign, certain enemy Iron Curtain Devices are dedicated to shielding certain enemy units or buildings. These targets are permanently invulnerable until the Iron Curtain is destroyed, but unless if specified otherwise they do not provide the Invulnerability superweapon.
- In Beautiful Mind, the Iron Curtain in the Latin Confederation base is dedicated to shielding the Psychic Amplifier, and it must be destroyed so the Amplifier can be attacked.
- In Sunlight, the Russian army will build an Iron Curtain and use it to shield their Dreadnoughts.
- The Iron Curtain becomes a buildable structure in Dragonstorm.
- In Singularity, an Iron Curtain is one of the targets to be destroyed.
- In Moonlight, the Russian army will build an Iron Curtain after the contents of the first Rocket Launch Bay has been extracted.
- In The Raven, there's an Iron Curtain Device near the White House which will fall under the player's control when the American rebels attack. At the end of the mission, as a Scout Raven flies over the Soviet General's command post and the map becomes shrouded, the timer of the Iron Curtain changes colour from red to violet.
- Two Iron Curtain Devices are the targets to be destroyed in Mind Over Matter. They do not provide the Invulnerability superweapon.
- In Stormbringer, the mind controlled Russian base has an Iron Curtain.
- In Thread of Dread, the Foehn base has an Iron Curtain in the farthest back, above the cliffs.
- In Machinehead, when the Proselyte attempts to use 16 Foxtrots to destroy the Centurion Siege Crawler, the attempt fails as the Centurion suddenly turns invulnerable. Libra is then deployed and tasked with destroying the Foehn Iron Curtain, but once it is, the Centurion remains invulnerable and it's revealed that it has its own portable Iron Curtain Device.
- In Meltdown, the Psychic Dominator is permanently shielded by an Iron Curtain. The Iron Curtain is protected by a large number of EMP Mines, and, unlike the ones in Beautiful Mind and Kill the Messenger, can still be normally used to turn vehicles invulnerable. Unlike normal superweapons, this particular Iron Curtain can be captured by Engineers, which will also cause its timer to reset.
- In Kill the Messenger, the vehicles and defences guarding the Ironwing are invulnerable until the Iron Curtain shielding them is destroyed. While this Iron Curtain does not provide the Invulnerability superweapon, the Chinese will eventually build another Iron Curtain that does.
- In Hypothermia, the mind controlled Latin Confederation has an Iron Curtain that does not provide the Invulnerability superweapon.
Behind the scenes
- Prior to 3.3 Invulnerability does not affect structures, can kill infantry and affects enemy units too.
- In versions 2.0x, the Iron Curtain Device used the design from Red Alert 2 alpha and beta phases.
- Rage Inductor
- Blast Furnace
- Blast Trench
- Iron Guard - A miniature version of the Iron Curtain that causes nearby friendly vehicles to become permanently invulnerable within its area of effect