Don't be afraid to shapeshift, hit the tank with a HoT, or even Rejuv pre-pull, will speed things up limiting the amount of heals your healer needs to push out and lower the chances of them getting initial pull heal aggro if tank takes a damage spike and requires a big heal.
You give buffs to all, and keep thorns on tank for more threat.
Innervate the healer on CD, if their mana is typically high, hit the mage with it to keep things going.
If tank dies, you can pick it up in bear. If healer dies, you can pick it up with heals.