If you need healing return home. If you die, the respawn time is usually longer than the time you would have used to go back to heal.
Heroes
You can get a random hero as a reward by logging in daily for seven consecutive days. Use the free daily hero to test them out and decide which one you would like to unlock next. There are five different classes that are available; tank, support, mage, fighter and assassin. Each hero has five abilities that can used in battle. They also may have some abilities that have better effects if used in a specific order.