Mission 1: The Return of Tassadar--
Tassadar's older brother, Elranor, returns from
a 200-year-long search for signs of the ancient Xel'Naga, convinced that
his brother's knowledge is the key to finding the enigmatic race.
Investigating the circumstances of Tassadar's death, he finds that the
psychic Khaydarin Crystal used to bring the Overmind to Aiur may contain
the psychic awareness of his brother. He seeks out the Executor and
persuades him to recapture the crystal from Kerrigan's Zerg, then draws
upon the crystal's powers to form an Archon with the residue of Tassadar's
personality. The Archon, Tassadar/Elranor, escapes with the Executor's
fleet into deep space.
Mission 2: Quest for the Xel'Naga--
After discovering that an ancient Xel'Naga warp
portal exists on the former Protoss planet of Aiur, Tassadar/Elranor convinces
the Executor to recapture the portal from the Khar'Alun Brotherhood, a
Protoss sect that remained on Aiur after its abandonment. Boarding
the carrier Rexallar, he pilots it through the portal.
Mission 3: The Pursuit Begins--
Queen Sarah Kerrigan, who has learned of Tassadar/Elranor's
mission to find the Xel'Naga, decides to pursue him to the Xel'Naga planet.
She attacks Jim Raynor's space station, capturing a data disc that contains
the readings on the Xel'Naga portal's emanations prior to the Archon's
departure. From this data, she is able to discover Tassadar/Elranor's
destination.
Mission 4: Expeditionary Force--
Arriving on the Xel'Naga planet, Tassadar/Elranor
and the Captain of the Rexallar reactivate the ancient Protoss ruins
there, then use these buildings to construct a small army and clear the
area of Zerg.
Mission 5: Renegade Brood--
Kerrigan arrives on the Xel'Naga planet, only to
find that the local Zerg are not loyal to her, but instead follow the devious
Cerebrate Ultor. Spawning an army of Zerg, she forces Ultor to submit
to her will. Soon after, however, the Zerg forces are attacked by
a Protoss fleet bearing Xel'Naga markings and led by a Templar named Kolvan,
who claims to be one of the Guardians of the Xel'Naga. The Zerg destroy
Kolvan's fleet.
Mission 6: The Guardians--
Tassadar/Elranor receives a transmission from Kolvan,
leader of the Guardians of the Xel'Naga, a group of Protoss who remained
in servitude after the race rebelled against Xel'Naga control. Kolvan
tells Tassadar/Elranor that his main fleet has been destroyed by the Zerg,
and that his troops will soon be overrun unless they receive help.
Tassadar/Elranor and the Captain save Kolvan's base, then capture a relic,
the Genesis Tank, which allows the Archon to spawn an immortal copy of
himself called an Avatar.
Mission 7: The Avatar--
The invulnerable Avatar of Tassadar/Elranor wreaks
havoc among the Zerg swarms of Kerrigan and Ultor. It challenges
Kerrigan to single combat, but when she declines, it attacks her main Zerg
force. Ultor tells Kerrigan that the Genesis Tank is the source of
the Avatar's power, and she destroys it. Instantly, the Avatar disappears.
Ultor, however, has betrayed Kerrigan, and gloats that, with the help of
another Xel'Naga artifact, the galaxy will soon be his.
Mission 8: Dreadnought--
Ultor has captured a titanic Xel'Naga warship that
he discovered in orbit. He begins to charge the ship's main guns,
threatening to destroy the planet below. Kerrigan uses a warp bubble
to escape the doomed planet, leaving only the Protoss to resist Ultor's
new-found relic of power.