[Taqwus]

Items which mimic spells can do so in three ways -- some autocast once at the beginning of combat, some autocast throughout a battle, and some are invoked by the commander in lieu of a normal action.

Most items that summon monsters are autocast-once items, with the notable exception of the skelispam talisman. Wraith Crowns, the Corpse Candle shield, the Soulstone of the Wolves (used to be action-based), the Pocket Lich, the Headless Hoburg, Percival the Pocket Knight... all autocast-once.

The Bag of Winds, waaaay back, was an action-based item, but this was judged to be unbalancing. A commander with a quickness effect could spam multiple air elementals per turn, which was a bit powerful for the cost.