This Seeking Tech guide will show you how to get the Caster’s Nightmare trophy in Jeanne d’Arc. This trophy will unlock when you eliminate a party member by casting Earthquake.
To get the Earthquake skill, you can combine Body Slam with Thor’s Hammer via Skill Binding.
The Body Slam skill can be dropped from the Golem enemies. You can find these in Chalons.
Thor’s Hammer can be dropped from the Lich. You can find these at the Langles Tunnel.
Alternatively, If you are in the post-game, then you can get the Earthquake skill stone by completing the Free Combat stage in Soldat Outpost.
Once you have Earthquake equipped, head into a fight and then wait until you have enough MP to cast it. At least one of your party members should have low health as well.
If your Earthquake attack eliminate at least one party member, then you should get this trophy.