An Esper Troupe is a method of organizing Yarhi for battle in Final Fantasy XII: Revenant Wings. An Esper Troupe consists of five slots in which the player can place different species of Yarhi according to Rank. The player can access this feature by selecting "Esper" from the menu, at which three different Esper Troupes will appear.
At first, each slot can only hold Rank I Yarhi, and three of the slots are filled in with the weak non-elemental summons Alraune, Sylph, and Garchimacera. As the player accesses more Espers through the Ring of Pacts, they can fill in the slots with any Yarhi provided that the Rank restriction is followed. Once the player obtains their first Rank II Esper, the rightmost slot will change to II, which means the player may insert Rank II Espers and below into that slot. Two more slots may be changed once a Pact is made with two more Rank II Espers, resulting in a Troupe of two Rank I slots and three Rank II slots. Once the player's first Rank III Esper is obtained, the rightmost slot changes to III, which all ranks of Espers can inhabit. This is the final Esper Troupe level:
- Two Rank I slots
- Two Rank II slots
- One Rank III slot
Once a Troupe has been assigned and the battle has begun, Espers from the selected Troupe will appear when Vaan uses the Cache of Glabados. In a standard five-leader battle, the following rules apply:
- Each group leader will have two Espers immediately join their group.
- The identity of the Esper depends on the nature of the group leader. Vaan and other melee units will be assigned melee Espers (excluding Rank III of course), ranged units such as Kytes will be assigned ranged Espers, Penelo will be assigned Holy-elemental Espers such as White Hare, and flying units such as Filo will be assigned flying units.
- Rank III Espers can only be summoned through Summoning Gates and so will not appear at the battle's start.
- Of the remaining Rank I and Rank II Espers, the highest rank possible will be assigned. For example, if a Sagittarius and Shivan are in the same Esper Troupe, each ranged group leader will be assigned two Sagittarius.
- If there is a tie in rank, say a Sagittarius and a Shivar are in the same Troupe, one of each Esper per group leader will be summoned at the battle's start.