"Monster Lure" Spell

How would you go about making a spell that is like Monster Lure, (you put a ward down and it attracts nearby units to it) and when they reach it, the ward explodes dealing damage. I'm thinking basing it off of Landmine, but thats about as far as I got :).



EDIT: Er, sorry this is a different spell. I meant to ask why won't this work?
Events
Unit - A unit Begins casting an ability
Conditions
(Ability being cast) Equal to Seal Call
Actions
Unit Group - Pick every unit in (Units within 1000.00 of (Position of (Casting unit)) matching ((Owner of (Picked unit)) Equal to Neutral Passive)) and do (Unit - Order (Picked unit) to Follow (Casting unit))


Thanks.

You can do this, make a spell off of like some ward of summon spell. Then make a unit with the ability that the mountain giant has that attracts em. then do

Event - Unit enters (entire map)
Condition - Entering unit is equal to (the unit u make)
Action- Order Entering unit to (use the spell of the mountain giant or u make a new one)

Oh I see, so give the Monster Lure the taunt spell?

ya then edit it to how u like it