Stances are any instant-activation skill that provide a passive bonus for
your character, such as the chance to block attacks, increased attack speed,
increased running speed, increased recharge rate for Adrenaline, and much
more. Some damage mods, such as +15% Damage While in a Stance, -2 Damage While
in a Stance, +45 Health While in a Stance, and more of these make Stances
even better. Stances are also the staple skills for a W/Mo Tank. Unlike
Enchantments, Stances are very hard to remove, and there is only one skill
to remove a Stance that is a Warrior-Only skill: Wild Blow.

EXAMPLE: A Tank that doesn’t use Stances is indeed a crappy Tank.