Similar to tutorial 06 and previous tutorial. The fire boomerang will need different movement route commands depending on the direction of the player.
The effect we want to achieve is the boomerang to travel in a circle and go back to the player.
To do this, it's very simple. Simply combine move left right up down and upper and lower. Do similar commands in other directions.
There's no rule, no restriction. Be creative about how your ability will work and move and find the right commands, both from Action Combat and from default RPG Maker commands to achieve your result.