I think seeing as Shadowheart is one of the first npc you encounter and how limited we are for options i think there should be an effort put in for greater parity between the offical books and how the game handles the trickery clerics channel divinity.

Channel Divinity: Invoke duplicity
Starting at 2nd level, you can use your Channel Divinity to create an illusory duplicate of yourself.

As an action, you create a perfect illusion of yourself that lasts for 1 minute, or until you lose your concentration (as if you were concentrating on a spell). The illusion appears in an unoccupied space that you can see within 30 feet of you. As a bonus action on your turn, you can move the illusion up to 30 feet to a space you can see, but it must remain within 120 feet of you.

For the duration, you can cast spells as though you were in the illusion's space, but you must use your own senses. Additionally, when both you and your illusion are within 5 feet of a creature that can see the illusion, you have advantage on attack rolls against that creature, given how distracting the illusion is to the target.

As of now in the game it is a stationary training dummy that grants advantage to allies within close proximity.

I've used the power once and i doubt i will again. With how large the maps are, and agile the enemies are, without spending considerable resources managing the battlefield a stationary dummy that does not attract attention to itself will rarely be useful.