Scenario Design
    Wizards and Kingdoms and Things

The AI Block thing prevents AI-controlled units (both AI players and independents) from passing through the marked tiles.

Use the AI Block to keep AI players and independents from wandering into areas where you don't want them to go. When playing the game the AI Block tiles are not visible.

The path is blocked.

The AI controlled units cannot get to the mine.

The AI Block thing is found on the Places Tab in the editor.

The AI Block thing is removed from the map during gameplay when a human controlled army is moved through the hexagon where it is placed.

"I modified a map to test scripts and other things. I totally blocked off an area to keep independents from getting to an AI player, and they didn't, until I sent a unit through the blocks. It blocked the independents from getting in, and it blocked the AI player from getting out.

"Do this: put a group of very strong independents in a confined area with a city controlled by an AI player or yourself, surround the city with AI blocks, so that nothing gets in or out. Let the turns go as long as you want, then send one of your units all the way through the block, not just on top of it, and watch the independents go through the hole you made. BTW, make the independents raiders or berzerk, and set the map on aggressive independents." - Drakken

To get around this, you might want to use a script to make a customized (and more permanent) block. For more information on how to do this, read the article A Custom AI Block Using the "Teleport" Event

(This article was adapted from a scenario design forum topic.)