Human players have access to the Patrocross variable unit. The unit charges its wave cannon in fighter form, but strangely enough, doesn't lose its charge when it's in robot form.

If your Patrocross will end its movement near the fog of war or in the enemy's weapon range, transform it into the robot form at the end of the turn to "save" the cannon charge. If your Patrocross survives the enemy attack, transform it at the start of your next turn, and fire the wave cannon.