When the player digs in the correct spot I want there to be a special message and then have to fight some creatures before getting it. I tried adding the message to the custom properties as well as the creatures but when I tested it, nothing happened, just the regualr message and no battle.
Then I tried it for a regular artifact...nothing.

Anyone know why adding an army or message to an artifact has seemingly NO effect?

I dont know the answer to your problem but I have another question.

How can I place the grail randomly?I mean since I am the map maker I will always now the location so I want it randomly placed on the map.

Well you need a script here Lazyness has got into me so you should figure it out yourself

I was afraid you were going to say that. The message property works on monster objects (I just tested it), I think it should work on artifacts as well!
If anyone knows how to get it to work, please help!
Thanks in advance.

Huh? No, I'm pretty sure that when you place it, you can give it a tile-radius.
Place it wherever, but make it's possible location in a radius equal to the number of tiles on the map.
So if you're on a 128×128 map (that's still a size, right?), place it around the middle (just to make sure, in case of poor scripting in the map editor) and give it a possible placement radius of 128.
That should work.

I'll give that a go.. didn't realise you could set a placement radius. thanks!