Jack, the owner of the Reboldoeux stone pit. His multitude of scars shows that the effort he has put into maintaining his stone pit. He uses the construction stance to assist other members, and possesses a strong attack.
Increases the ATK SPD of your own structure by changing the mode, however, DEF will decrease. It will be cancelled when you re-use it.
A stance to create traps with various effects. This has many varied uses depending on the effects of individual trap.

Reveals invisible characters and locates hidden object

Builds a trap that releases a poisonous cloud of smoke when triggered

Set a booby trap that deals physical damage to enemies. (Also applicable to flying monsters.)

Sets an explosive trap that blocks attacks from several enemies at the same time
A sapper stance to set up an instant combat facility. This has many varied uses depending on the effects of individual facility.

Builds a fence that obstructs enemy movement and prevents them from advancing

Constructs a cannon-turret that automatically attacks enemies

Creates a protective ward that defends the characters within

Creates a regenerative ward that continuously restores the HP of characters within

Builds a Siegecannon-Turret that is able to attack several enemies simultaneously
A piercing stance for the Spear. It has a long range and uses swift, simple movements, making it advantageous for one-on-one combat.

Thrusts spear upwards to attack airborne enemies. Ineffective on enemies on the ground.

A series of stabs and pierces with a spear

Charges through a group of enemies with lightning speed