Testing... Testing... One, Two...
The quest is unlocked after completing the Terrako's Return quest. Completing this quest will unlock a series of other Terrako quests, including Learning from the Best, Preserving for Posterity, Unrelenting Power, Fragmented Memories, Terrako, Enlightened, Tough as Nails, Tougher than Nails, and Slightly Less Tougher than Nails...
"You finally managed to restore Terrako! To ensure the plucky automaton is ready to roam free, a few tests will have to be run. Rummage up an ancient screw to use in testing."
"After a full battery of tests, you confirmed that Terrako was in tip-top shape! What's more, as it was regaling everyone with a cheery tune, the little Guardian showed off a new move!"
- Terrako: Bonus Combo