You recover your 5 wrath stack in 17-19 secs, so theoretically you have 20% damage mitigation for 6 seconds every 18 secs, so roughly you have a 20% mitigation for 1/3 of your time passed as a war, obv if you don't use overpower, flash etc. Then, storm's path, absorbs 50% of damage, and that's a shit, you will recover more or less 100-120 HP, BUT the enemy will deal 10% less damage for 20 secs, and that's a lot, the enemy you are fighting should have always that debuff on, especially if it's a boss. Vengenace, delivers an attack with a potency of bla bla bla, it's not that much, can be "good" with bloodbath for extra HP (more or less 15 HP per hit, WOW), but yeah, it's not special for that, it's special for a huge 30% of mitigation, it's a "oh shit" moment CD, and it's very good, also it gives you one wrath stack, so you can pop IB faster.