I respecced Shadowheart to have more strength initially, and a reroll later after finding certain gloves, and made her a tank with spirit guardian. Stays in range of other characters for more potent touch heals, can take a blow, and Spirit Guardians in the middle of a pack of a restraining CC spell, and it builds up the damage. Freedom of movement, or equipment that grants the same/similar are super useful for this strategy. That said, I have only played on the Balanced setting, so take it with a grain of salt.
Edited to add, Life domain provides juicier heals and access to heavy armor.