After you get all the functions (level 14 I think), you won't use Turn() in most cases, as you can spam super powerful moves and win easy.
For the Performance Tests and the Risk() trophy, spam Void with Tap and Purge as upgrades for constant healing to max hp. You can also use Spark with Bounce and Cull for good damage in between casting Void. Put Flood and Load in Passive slots, flood will heal you and Load will drop off bombs to be set off by Spark. Mask can be used in the 3rd slot in case you get in a jam. You may get unlucky with your early round functions. If you can get Spark with Purge, it makes earlier rounds easier.
For the Agency Tests you will need to use Turn. Just use Void 3 times followed by Mask, striking with Cull for an instant kill. You can use Breach and Ping in Passive slots to enhance your Turn().