Heres adding to what they've already said. What you do, if you copy all the heroes, and make an item with a dummy skill( it will ahve to be useable, but thats not too bad). Then you create a trigger that identifies who uses the item, be it crypt lord, or paladin, or whatever. Depending on the user, trigger so it will give him/her a specific metamorphesis-based skill that corresponds with them (you'll have to make a model for each hero). Just make it give them the meta-ability when they use the item and order them to cast it and remove it quickly. Change the buff, and you're set for an item that can allow heroes to walk on water.( just make sure the meta'd units CAN walk on water; you'll just have to change their movement type)