Focusing current target based on name

[RaxleMF]

I've been trying to figure out how to have a macro that will set my target as my focus, but only if it's my Soul Effigy (Warlock Level 100 talent).

The idea is that I tie this event in with my Agony button so that when I cast Agony, it will also automatically focus the target if it's my Soul Effigy. Something along the lines of:

#showtooltip
/cast [mod:alt,@focus][] Agony
/run local (Insert script here)

The script would check if my current target's name is Soul Effigy, and if so, set it as my focus.

Thanks in advance for any and all help!