[the_matrix_walker]

The easiest usage is the Impulse buys version, giving the target points to spend for the afflicted advantage version, and points used against them for the afflicted disadvantage.

You cannot afflict a specific destiny, as normally the GM determines a Destiny in secret. You'd likely need to extend the duration to permanent because Destiny's don't become fulfilled overnight.

I think this is the wrong way to go for a Geas. Mind Control with conditioning can implant a Compulsive Behavior or obsession. or you can Afflict those disadvantages.

If you want to get a little closer to a geas, you can use affliction to grant the Cursed disadvantage, with a mitigator. The daily "treatment" to satisfy the mitigator would be pursuing the stated order of the geas. I find that feels right with the historic "follow your geas to avoid your doom" stories.