Guild Titles bonuses of each class per level.
For example a level 10 Paladin gives +30 armor to all of your characters.

Paladin: +3 Armor
Ranger: +3 Weapon Power
Sorcerer: +0.1 Mana Regen
Warlock: +3 Resistance
Rogue: +0.75% Reduced trap damage
Wizard: +3 Spell Power
Warrior: +3 Health