Hmm, i never had bugs with it. 2 units can't cast a spell really at one time. Are dummies really needed in this case?
And, if you need taunt, there is the 3rd solution. You can make an ability from roar ('Aroa'), and order nearby enemies to attack you. (You can set a defence increase bonus for roar. To make it influence only one unit, you can change targets - self only, or effect range - to 0).