I. PORTAL OVERVIEW
The Portal is a device that is used to bring more people to the battle scene. Considering that there is a war between the Order and the Chosen, they have the ability to build or bring in Portals so that they have more people for combat. Without one the combatants would be all alone.


The Order's portal

The Chosen's portal

When your portal is destroyed the game ends and you lose the round. Another good reason to defend it is because you always respawn at the portal. When you die you are thrown into a queue, and while it counts down everyone that dies gets thrown into the countdown with you. When the countdown reaches zero, everyone who has died will spawn near the Portal. Thus defending the portal prevents Spawn Killers! The portal can be healed by the Mage or Android using the "Mend" or "Repair" skill(depending on your alignment).

II. WHY DOES THE SHIELD PULSATE AT DIFFERENT SPEEDS?
The shield pulsates faster as the portal gets closer to spawning players. This is warning for attackers to run, as respawning players will have the advantage of limited spawn invulnerability.

III. RESPAWN RATE
A player's respawn rate varies with the health of the Portal. The Portal can be repaired by the following methods:
Android's Repair Skill
Mage's Mend Skill
Wastelander/Monk Aura Minor Skill
Cyborg's Charge Station Skill
Fighter's Shrine Skill
Mass Repair Prayer (can only repair to 8000 HP)

By repairing, the queue can be dropped to 1 second! Look at the chart below for some respawn times (as of Purge Jihad 2.0.3):

IV. SUPER PORTAL
A Super Portal is in divinely protected portal that cannot be damaged, but it can be repaired to 9999 HP. There are two ways the Portal can be a Super Portal:
When the round starts, the Portal will be a Super Portal for the first 3 minutes of the round. Thus there is little incentive to rush the enemy Portal early since the Portal cannot be damaged during this time. Your team should spend the time building defenses.
The server can optionally choose to a Super Portal game where the Portal remains invulnerable forever. The Portal will also start 9999 HP in this mode, effectively taking the Portal strategically out of the game. This mode is not recommended and is mainly for tactics-free, "deathmatch-like" games.

V. SPAWN INVULNERBILITY
When you spawn you are invulnerable. This is to protect players from spawn killers. Your invulernability is shortened to a few seconds if you move too far from your spawn point, use weapons or skills, or too much time passes. While you are invulnerable, you will appear in translucent shadows.