The RTS behavior has an implementation of A* pathfinding which is pretty good for navigating around complex maps. There's also stuff like intelligent aiming you might find interesting (see the attachment further down the thread - the maths in the original file has since been built in to Construct).
Construct's event system is also very capable of coming up with an AI system. It is, however, entirely up to you to code it. Quite often questions along the lines of "How do I make AI?" are asked, which is too vague to answer. I think you can make a fairly good AI system in a much simpler way than most people think. All it is is automatically controlled enemy characters - it's easy to come up with some simple rules that make them interesting enemies in gameplay.