Select the support magic that you wish to cast. The amount of magic that can be cast is limited by the Chamberlain's MP.
The Chamberlain's MP is currently .

Wind Walk Lv.2 Decrease Weight Lv.3 Shield Lv.3 Mental Shield Lv.4 Might Lv.3
Bless the Body Lv.2 Magic Barrier Lv.1 Resist Shock Lv.1 Bless the Soul Lv.2