I came up with two abilities in my RPG project, both belonging to the tank of the party. They're called True Grit and Bloodbath. True Grit makes the user completely invincible, but every turn he loses 25% of his HP and cannot be healed while under its effect. Bloodbath has the same 25% HP drain, but the buff instead raises his critical hit rate to 100% while in effect. (For reference, Critical hits deal 150% of the final calculated damage, after the enemy's defense is already taken into account) Are these skills overpowered? Underpowered? Should I crank up the HP drain to 33%? I should point out that the HP loss happens after each action, not necessarily each turn, so the turn he first casts True Grit or Bloodbath doesn't count.