Question on order of heroes' spells

Sorry for a noob question, but do the heroes use their spells and abilities in a set priority (from left to right) on the toolbar? If I want a particular spell to be one of the first they rely on, does it have to be in one of the first slots on the toolbar?

Nope, they use it based on the programmed hero AI.

To put a little more on that, each skill has a set of criteria for when it should be used. The hero AI will always try to use any skill when its criteria are met. (And most of the problems with the AI spring from the fact that these criteria are not particularly good reflections of how a human would decide whether to use a given skill.) It has been speculated, but not confirmed, that, when the criteria for using two or more different skills are met at the same time, the hero AI will use the left-most one of those first.

When conditions are met for multiple skills there is a prioritization that ranks the likelihood of various skills to be used. The priority only increases the chance of being randomly selected, and in many cases does not garuntee that one skill is used over another.

I'm 99% certain that left to right has no influence on the hero skill usage. Its a mere fantasy that people like to believe because human skill bars generally put priority skills on the leftmost side. If I could find a way to actually have my monks spam Healing Burst on recharge rather than Dwayna's Kiss I would be the God of guild wars.

Best you can do is disable some skills or micro manage the hero and cast that skill yourself.

People forget that this is a computer program. It's almost a certainty that the hero's skillset exists in an array, and the the skill choice algorithm iterates down that array. (Simultaneous and un-ordered behavior are not possible without multi-threading - which GW is not.) Since there must be some ordering, why not left-to-right? It seems just as likely as right-to-left, LIFO, FIFO, and whatever-order-they-are-indexed-in-the-dat. (And that is just about every way I can think of to order the skills.)

A related issue that may be confusing people is that the criteria for using a given skill may use the presence of other skills as an input. For example, the AI seems to consider the presence of DKiss with <2sec left on its recharge as a reason not to cast Infuse in many circumstances where it would cast Infuse if DKiss wasn't there. This is not a true case of two skills having their criteria met at the same time.

A good test, if anyone wants to do one, would be to load up a hero with nothing but a pair of clone skills (ex: desecrate enchants and defile enchants) and see if here's anything you can do to change the order of usage.

Interesting. Thanks for the replies.