Why does the ai EVER choose Fire Flies?

[tinkthank]

I dont understand why the computer EVER selects Fire Flies as a spell to cast once Evocation 1 is researched. Fire Flies cost 20- fatigue, does 6ap damage, has -1 precision, a range of 25+, and requires 1 fire. Fire Darts has identical stats, but does 10ap damage and has +4 precision. Obviously, Fire Darts is better in all ways to Fire Flies, which is also represented by the fact that you have to research Fire Darts in order to cast it, while any pyrodork can cast Fire Flies out of the box. Yet once scripts run out, or if none are chosen, the computer will more often cast Fire Flies instead of Fire Darts. But why, if it doesnt save fatigue? And if Fire Flies is actually a better choice for some other (which?) reason – why is it a freebie?