Ability help

I have this ability, and I need to use triggers to create its art. But since its based from entangle I need it to stay longer for each level. So I create a trigger to get its level. I know each skill has a special code, entangles would be AEer so would that be the same as my custom skill based off of it? The thing I'm not sure of is the event I would use to find when my hero casts the spell so I can run my special effects, and I also need to know if the code is the same even though its custom.

I am not positive what you are asking but here is a few different things.
First
Open up the ability editor and press Ctrl+d. Each spell should now have 2, 4 letter codes by them; the first four letter code (probably something like this A00B or A006) next to your custom spell is it's four letter code, the second is the spell it is based off of, use the first.
Second
Use the event Unit is issued an order targeting an object. Now under conditions use (Issued order) equal to (<the order string of your spell>) and (unit-type of OrderedUnit) equal to (<your hero with the spell>)