ToME: the Tales of Maj'Eyal

Is it intended behavior, or bug?

Edit: Now I'm not really sure about it. Targeting take 1 turn though, unlike normal spells

It's not taking 2 turns. It's taking one turn but your turn is used as soon as you activate an item. If the item requires targeting you're using the turn, the monsters go, and then you target and the effect takes place. Then you go again.

It's an order disconnect. All items work this way.