Here's a great idea. Why don't we make a living spell grease and then we could let it cast wail of the banshee... Sounds pretty stupid and kinda like deliberate griefing of the players right? So why then is there a living spell delayed blast fireball in kobold that casts that and scorching ray? No matter how good your save is you have a 5 percent chance of failing it and that alone argues for this being a dirty tactic to make sure players take damage but there is more to it that that. A character that has evasion has given up something for it. Whether it is casting ability, BA, base hit points, whatever. Oh, and it gets worse..if evasion is so OP that you need to circumvent it why do so many mobs have it? Finally, the trivial point, it a a "living fireball spell" that casts something else...suspension of disbelief fail. Its stretched with a living spell that casts that spell, it is in my opinion exceeded with them becoming mages that accurately identify target weakness such that they use rays on those that will save against their fireballs.