In my game in which I'm the Mercenaries versus the Shadow Elves, my Apprentice Mage moves adjacent to Selundar during the Move phase. During the Attack phase, the Apprentice Mage's image is highlighted (as well as being outlined in red), meaning I can use his Magic Shot to spend 1 Magic Point to add 1 to its Attack Value. Typically, when choosing to use a Unit's Special Ability, dragging the highlighted image onto the target shows an "S" shield instead of a numeric shield. In this case, a "1" shield displayed as I dragged the Appprentice Mage's image onto Selundar. I figured the app would automatically spend 1 Magic Point and roll two dice. Instead, it spent 1 Magic Point and rolled only one die.
I captured a screenshot at the moment the Magic Point was spent and the die rolled. I'll email it to firstname.lastname@example.org and reference this post. You can see the Magic Point that was spent hovering over my Discard pile and the successful single die roll.
I think the fix should be to allow the player to drag the highlighted Apprentice Mage image onto the target and display an "S" shield icon, so the player knows the app intends to use the Unit's Special Ability.
EDIT: It was explained to me that one has to drag the left side of the card for a melee attack and the highlighted character for a ranged attack. Knowing that, it makes some sense, but it's not very intuitive, IMO.