|tyrant is damaging an important resource supply. Take down Si-el, the Vacuous before we lose any more of it.|
|Prerequisites: Chapter 3 completed, BLADE Level 7|
| Objectives: |
| Rewards: |
|Results: "You slew Si-el, the Vacuous in Noctilum."|
Si-el, the Vacuous is a Basic Mission in Xenoblade Chronicles X. It is a request from the Prospectors and the primary destination is Noctilum. It is a request to defeat the titular Si-el, the Vacuous.