I'm working on a small project for which I need a creature which uses hostile spells frequently but never its melee attack. Basically, it has one target spell which I want it to cast once every one or two seconds at its enemies. Does anyone know how to make a combat style in the construction set that will do this?

Have you tried emptying their inventory? I.e. remove all weapons? If they don't have any melee items in there then they cannot use them!

Also, I'm pretty sure mage characters (hedgewizards for example) tend to flee and use magic instead of actually battling it out with the player.

You might want to look at their profiles in the CS and compare them to your NPC. I'm not sure if the setting 'combat style' has a huge influence on battle, but changing it to suit a mage character may help.

EDIT: I just noticed you used the term 'creature' instead of character (my bad), so it isn't an NPC?

Well, in the animations if you untick certain combat moves then I'm pretty sure they won't use them.

You would first need to make sure the creature you're using can cast spell (i.e. Goblin Shaman, Ghost, Wraith, Lich, etc). Then set its combat style. Some combat styles to consider are:

DefaultGoblinShaman
DefaultLich
DefaultLichNether
Any of the DefaultWraith styles (there are 5 to choose from)

Basically any creature style with the "Prefers Ranged" flag checked. See http://cs.elderscrolls.com/constwiki/index.php/Combat_Style on the CS Wiki for more.

I didn't mention this before, but just in case it is important, the creature is unable to move, so it will not be able to choose the distance it attack from. If attacked by a melee enemy, it will be forced to stand still.

Edit: Nevermind. I figured it out. Thank you.