Save Sacred Soil to use during stomps (especially if you can remember the pattern). That's where most of the party damage comes from, and doing that will help the MP and enmity management of both healers. If the other healer is a WHM, their primary role is helping the party up (Cure III and Medica II are their bread and butter) while yours is preventing the damage from happening in the first place. As was said before, you'll also want to use Virus to reduce the damage of mountain buster (the heavy tank attack), and also Adloquioum the tank beforehand if possible.