The Strike spell allows you to use an illusion to attack. However, the "Flyswatter of Doom" approach seems to have been removed in the transition from RM2 to RMSS. In RM2, when casting an Illusion N spell, you got N options, which include such things as adding senses or doubling the damage from a Feel Mirage. Thus, with Illusion X, you could 1) add a feel sense and 2) double the damage 9 times (for x512 damage). In this manner, it's not hard to inflict a few thousand points of damage. A quick scan of RMSS spells suggests that this abuse has been negated.