Hi,
I found HSRanger plays preparation *just* to activate combo.
For example, Knife Juggler 3/2 on enemy board and I have SI Agent and Preparation in my hand.
Then it plays Preparation and Agent to kill Juggler with Agent's combo even if I didin't have another spell to use.
It's maybe a reasonable move, but I think its a wasteful use of Preparation.
Regards.