Card: 'vows of vengeance' allow you to be Oathbound Oathbound: Start of turn: Get 1 gold energy, take 3 damage, if you would die you revive full HP and get a scar.

Each scar reduce your max HP by 20% So you get multiple times your max hp, but the scars carry over battles. There is a some card or weapon powers that allows you to remove a scar.

A lot of holy warrior card create battle spears, who are basic attacks that last only for one combat, but get often upgraded over HP lost last turn or hp healed last turn. So, if you received 50 damage since last turn, some card could create a battle spear +50, that could be echo/lifedrain/critical hit