Items & Triggers

Im making a hero arena map, It's based in 3 different terrains, Ice, Forest and Desert. Im making an orb of [Something] For each area. Desert has fire and Ice has frost. I didn't think that lightning was appropriate so I've edited the Orb of fire Icon to make it green. I've started to make the spell (Well, Trigger), I want it to have a 5% Chance that units that attack the hero holding the orb will be entangled with roots. I've got everything going but the action for the trigger, could anyone tell me how I would go about making something like this, without having to make every hero know entangle?

Hmm, Ok, Ive gotten a few things worked out. But can someone tell me what word to use rather that "overhead" to place a specaial effect at a units feet? Rather than above it?

Try origin or foot.

Isnt "origin" center of the unit, That should work i think

Thanks! It works great now.