Basicaly the idea of the cage is make a place where units will be spawned and will be trapped between the builds.
The units spawned inside the cage will be a possible target of some enemy legendary/special builds. When the spell target the units inside the cage, will be protecting your main army to be hit by those spells.
To the cage work need to be activated the mode -ca.
Exist a huge number of possible ways to make a cage. Each player can have his own style to do it. To build a cage you need to find a way to trap the units spawned inside it. You can use your own special builds to start it.
Below has some examples of cage: 1) At this cage was used the Ceremonial Totem do block the way and trap the Kodos.
2) At this cage you can see a lot of trapped Kodos by Ceremonial Totem and the build Falcon-Clan Encampment (Wyvern Rider unit).
3) At this cage was used differentes types of builds to trap the Zombies. To do this cage need to use the Rally Point carefully.
4) At this cage was used the Shamanic Tent (Shaman unit) to block the grunts.
5) This cage was a combination with a 434 Power Plant.
This depends of what kind of especial/legendary build you want to counter. There are three types of units to build inside the cage:
1) Cheap units (in general the most used type of unit). Good side: few gold cost and fast spawn time Bad side: can feed the enemy. Example of units: Footman, wolf, satyr, zombie, murlocs, spiders, grunt.
2) Resistant units Good side: Harder to die and will be aimed more times. Bad side: Cost more gold and have a bigger spawn time Example of units: Banshe, Spellbreaker Kodo, Defender, Dryad
3) Healing units Good side: Harder to die and will be aimed more times. Bad side: Cost more gold and have a bigger spawn time Example of units: Sorceress, crusader, furbolg and dryad.
Below has table with counter suggestions for each type of special builds:
note: Obelisk of Light only hit the units inside the cage if the fog of war is disable or if something give vision the the enemy (example: converted unit or erased tentacles). Because the Ray of Light of the Obelisk of Light hit only visible units.
Yes. There is two options:
1) The naga builder can use the Coral Statue to keep healing all units inside the cage. That will deny feed to the enemy and will have more units to be aimed.
2) In some situatuions you can also use a tower to protect your cage and get feed. When the enemy is using the Naga build oracle of sirens (abiliy: control enemy). When the enemy is using the Corrupted build Forgotten One (ability tentacle prison). When the enemy is using the Undead build Skull Pile (ability: Raise Dead) and is spaming a lot of skeletons.
As soon has possible. Don't way until the enemy make special builds to start a cage. Start to build it aways when you can. You need to be ready to use it all the time. If you delay it, this can cost the victory of the battle.
The cage can be also used has a "tower" to defend the base. You need pick a good place to make the cage and set the rally point to trap units with good attack range. Below have two pictures showing how the cage can be used for this purpose:
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