I feel like your warlock knowledge is non existant. Warlocks get an overshield with their melee as well, radiance lets you spam grenades, take 50% less damage and lowers the cooldown of the entire raids grenades if you choose that perk. If you are relying on a blinding bubble to clear a raid, then you are a sub par player. The only thing a titan does in crotas end that both other classes cant do better, is distract boomers. Which can be done multiple other ways.