Rise of the Machinists

Quest giver: Stephanivien
Location: Foundation (X:8.1, Y:10.1)
Job: Machinist
Level: 60

Experience: 100,000
Gil: 1,656
Previous quest: Rusted Steel
Next quest: The Machinists' Choice
Patch: 3.0

“

Stephanivien has received word on the upcoming trial.

— In-game description

Rewards

1 Machinist's Armor Coffer (IL 210)

Unlocks

Walkthrough

See also: Artifact Armor

The coffer contents are the Artifact Armor for Heavensward, which is Item Level 210 former Allagan Tomestone of Esoterics gear. The coffer was added to this quest with the launch of Stormblood. The rest of the set is available at Yolaine in Foundation (X:13.1, Y:11.9) for Centurio Seals.

Solo Duty

Note that there are a number of NPC allies present in the scenario. If any of the named ones (Joye, Rostnsthal, Stephanivien, Celestaux, and later Tedalgrinche and the Ishgardian Priest) die, the scenario fails, so ensure you protect them.
A cutscene will play in which Tedalgrinche once again taunts you, introduces the Ishgardian priest, sets the rules of the trial, and the predicts your eminent brutal death, before retreating to a cliff above to watch the proceeding battle.
After a cutscene, you'll start facing a pack of smaller dragons. There will also be a larger pack behind you that will attack the NPCs running rear guard. Take care of the pack in front first, then run back and clear the pack attacking the NPCs behind your start point. The dragons have a number of point-black and conal AoE attacks with easily-dodged telegraphs, and otherwise don't present a significant threat.
At this point, another cutscene plays in which Tedalgrinche and the Ishgardian Priest are knocked off their cliff by the dragon Veri Selen, with Tedalgrinche's sword remaining lodged in the cliff above, leaving him and the priest defenseless. Stephanivien orders the machinists to defend the two fallen, and after more back-and-forth, you're faced with Veri Selen directly.
Veri Selen, like he smaller dragons, mostly attacks with telegraphed conal and point-blank AoE attacks that are easily dodged. Note, however, that there's two additional packs of dragons that spawn behind you, one attacking Celestaux and several other machinists, and one attacking Tedalgrinche directly. Attack Veri to gain aggro (Reassemble + Drill does the trick very well), then turn and retreat to the packs of enemies behind you. This allows you to AoE down all of the smaller enemies, then finish off Veri afterwards. Try to avoid pointing Veri (and if possible, the other dragons) at the named NPCs, but as long as you kill them all relatively quickly, it's not a substantial risk of failure.
Once Veri and the other dragons are dead, the duty completes. It may only require killing Veri directly, needs testing.
Another cutscene plays, in which Stephanivien is once again given a carte blanche and essentially asks for nothing but fluff. Proceed to /facepalm.

Steps

Speak with Rostnsthal.
Speak with Joye.
Speak with Celestaux.
Speak with Count Baurendouin de Haillenarte.
Speak with Stephanivien.
Speak with Stephanivien at Twinpools.
Defeat the dragons!
Protect Tedalgrinche and defeat the dragons!
Speak with Stephanivien at the Skysteel Manufactory.

Journal

Stephanivien has received word on the upcoming trial.

With the day of the trial near at hand, Stephanivien would host a feast in honor of his machinists' accomplishments. As has become customary, however, the principal players are nowhere to be found. Head out into Foundation, and locate Rostnsthal, Joye, Celestaux, and Count Baurendouin de Haillenarte.

You have found and spoken with Stephanivien's absent guests. The count, though he wishes his son well, has declined to attend. Return to the Skysteel Manufactory, and pass on his message to Stephanivien.

Stephanivien thanks you for summoning everyone to the feast, and speaks highly of your positive influence on the manufactory. It is time now, he vows, for the machinists to make their mark on history. Prepare yourself for a demanding battle, and join Stephanivien at Twinpools in the Coerthas western highlands.

In an unexpected turn of events, the machinists find themselves defending Tedalgrinche as they fight to defeat Veri Selen and its host of lesser minions. Upon the great beast's demise, the grateful noble at last recognizes machinistry's worth, and promises to work alongside the manufactory chief in building a place for the machinists in Ishgard. Return to the Skysteel Manufactory, and share this triumph with Stephanivien.

Stephanivien reflects on the events of the battle, and rejoices that the age of machinistry has at last arrived in Ishgard. With Rostnsthal's departure, however, he recognizes that there remain none in the workshop who can match your skill with a firearm. Take the lessons you have learned in the manufactory, and do your part in spreading the machinist trade to the farthest reaches of Eorzea!