This achievement is gained after completing all the Underfoot mission challenges.

Don't Fear The Destroyer Time Trial
Don't Fear The Destroyer Challenge of Toughness
No Mez for You!
Fungal Bloom Time Trial
Fungal Bloom Challenge of Toughness
Dependable Ally
Scent of a Woman Time Trial
Scent of a Woman Challenge of Toughness
Clockwork Apocalypse
Tasnise Underbelly Time Trial
Tasnise Underbelly Challenge of Toughness
Alphabet Goop
The Silent Schism Time Trial
The Silent Schism Challenge of Toughness
Burn The Heretics
To Serve Sporali Time Trial
To Serve Sporali Challenge of Toughness
Tilling the Soil
The Search for Saunk Time Trial
The Search for Saunk Challenge of Toughness
Shades of Extremism
Bonfire of The Adherents Time Trial
Bonfire of The Adherents Challenge of Toughness
Celebrity Roast
Seeding Frenzy Time Trial
Seeding Frenzy Challenge of Toughness
Gem Collector
Kill The Hatchlings Time Trial
Kill The Hatchlings Challenge of Toughness
Golem Hooky
Fire in The Hole Time Trial
Fire in The Hole Challenge of Toughness
Slaughter is as Slaughter Does
The First Corruption Time Trial
The First Corruption Challenge of Toughness
We Interrupt the Following Spellcast