Stances

Stances are a system that allows you to choose between different gameplay styles.
Depending on your current stance, you can switch between different mechanics that might better suit your playstyle.

It is possible to:

Use known spells with different elements
Trade defensive stats for offensive stats (and vice versa)
Boost your overall damage or healing
Use custom spells
And more...

Every core vocation (all except thief) has its own stances.
Below you can see the benefits (and disadvantages) you can obtain from them.