Ouros began to channel his essence into Sarah Kerrigan in order to complete her transformation into a xel'naga. However, this process would leave her exposed to Amon. Commander Jim Raynor was put in charge of coordinating her defense while she channeled Ouros's power, with Broodmother Zagara and Hierarch Artanis aiding her.
"Why would they? Tenacity is advantageous in war."
"That isn't what I- Ah hell nevermind."
As Kerrigan channeled Ouros's power, she was assaulted by void thrashers. She was able to use her newfound power to annihilate them, but such a power would stall her transfer. Kerrigan's allies set up defensive positions around her, while shadows of the Void came in from all directions. Raynor was forced to send forces to reinforce them before they fell. More void thrashers were summoned to assault Kerrigan, but were quickly dispatched.
Raynor held his position, and Kerrigan managed to channel the power, sending a blast that destroyed the shadows of the void in the area. Kerrigan ordered Zagara to take control of the Zerg Swarm, and to remember the lessons she had taught her.
- Ouros's last words(src)
Ouros departed the last of his essence to Kerrigan, stating the Infinite Cycle had now ended, and died. With the last of the xel'naga essence, Kerrigan changed form into that of a flaming angel, brimming with power. She sent a vision to Raynor, saying that the moments they had together would always be with her, but that they had to go. Raynor told her to finish this fight, and Kerrigan flew off to face Amon.
In this mission, the player spawns as the terran in the center, and has defenses on the western approach. Allies hold the east and southern approaches, but in limited number. The goal is to defend Kerrigan, and to keep allied forces alive as long as possible in order to use them as a buffer. Kerrigan can be used in a similar fashion to the Drakken laser drill from The Dig, but given the larger number of enemies it is recommended that she only be used for very high priority targets. First priority should be taking the expansion west of the starting base, in order to get the extra resources needed for a defense.
Wings of Liberty campaign units are available, and as such mercenaries should be called down whenever possible. Siege tanks, bunkers and missile turrets should defend the terran and protoss bases, while a mobile force should defend the zerg base. Structures cannot be built on the creep, but they will provide a stronger defense and Zagara will respawn when slain (Artanis will not) and as such does not need as much defense until later in the mission.
Use Kerrigan to take out void thrashers or high priority targets like brood lords that outrange static defenses. Try to avoid overusing it, as the last pushes are brutal and can come down to seconds.
On Brutal mode, bunkers will prove ineffective against the swarms of enemies that attack you due to their insufficient durability. It is better to make walls with planetary fortresses with siege tanks and SCVs behind them and nearby missile turrets. Vikings should also be used for anti-air defense (and killing colossi), as missile turrets will be regularly torn apart by enemy ground forces.
One unit that can prove particularly useful in this mission is the Spectre. The enemies that attack you will have no detectors, and since the Spectres have access to permanent cloaking, they can fire without fear of direct retaliation (only needing to worry about splash damage). A force of Spectres can prove highly effective at helping to defend Zagara's base, especially if you use their Psionic Lash attack on heavier targets.
As an added tactic, if you are in need of extra vespene gas, you can kill your allies' extractors and assimilators and build automated refineries in their place. Your allies will not suffer from a shortage of gas.
If you are trying to get the Purity of Purpose achievement, note that as long as Kerrigan's beam does not kill an enemy unit, it does not count against your limit. You can therefore use her beam to simply soften up a target, leaving it nearly dead and letting other units finish it off. This can be very tricky to manage, however, due to her beam's sheer damage.
|The Essence of Eternity|
Complete the “The Essence of Eternity” mission in the Legacy of the Void campaign.
|Praise the Sun!|
Kill 60 enemy units with Kerrigan’s Celestial Beam in “The Essence of Eternity” mission on Normal difficulty.
The achievement name is a reference to the action role playing game Dark Souls.
Complete "The Essence of Eternity" mission without allowing Kerrigan’s life to drop below 1500.
|Purity of Purpose|
Complete the "The Essence of Eternity" mission while killing no more than 15 enemy units with Kerrigan’s Celestial Beam on Hard difficulty.