How many times have you watched a troop go exactly the opposite way you wanted it to go? Pekka skirt around walls much? What I propose would be a spell that allows the player to select the units in a particular area and give them one target. Those troops will then abandon all else to attack the indicated target, regardless of their preconditioned prefered target. I believe this spell should initially cost under 100,000 elixer and be available starting with Spell Factory level 6.