Q:

How to make the turret focus the clone of Wukong? (decoy ability)

I know it's possible, but although I main Wukong I've never been able to do it properly.

A:

You cannot drop the aggro once you've gained it since the turret has True Vision and you become stealthed with your W and not Untargetable.
Your clone works pretty much like a Mordekaiser Ghost or a Shaco clone. It counts as a champion but also as a pet which puts it pretty high on the priority list of turrets.
The only way to get the turret to focus your clone is by using the ability right before the last of your minions dies. Also keep in mind that any damage to a champion before or after you cast your spell will let the turret focus you again which requires walking out of range in order to drop aggro.

