Final Fantasy XIII Cie'th Stone missions guide

Note: Missions 21 – 26 are required story missions and are impossible to miss as you ascend Taejin's Tower.

Mission 21: A Tremulous Terror

Rank: C
Mark: Gelatitan
Cie'th Stone location: Taejin's Tower – Second Tier
Mark location: Taejin's Tower – Second Tier
Reward: Speed Sash

This is the first of the mandatory missions you’ll need to finish in order to ascend this tower. You’ll receive this quest not from a Cie'th stone, but from a statue-like structure that promises to help you progress once you’ve killed the mark. Gelatitan is another flan-like enemy, and probably the biggest you’ve yet encountered. It’s weak to Thunder attacks, so go after it with the appropriate elemental strikes. It’s also possible to sneak up on Gelatitan from behind with patience and timing, giving you a huge boost in your efforts to stagger it.