Lull mez and charms - how do they work

[Yumyums Inmahtumtums]

Mezz doesn't have a chance of breaking early (at least on 1-50 mobs).

I find immobilize heavy on mana for the duration. Using lowest level roots in most situations gives me the most flexibility with mana use. Sometimes I have to cast it too many times but I find the duration is acceptable for most encounters.