Citadel stat bonus for reference:
you can add 1 point in seven categories each time you level up the citadel, in a fixed order - so you can only put a point on one category every 7 levels.
below is the order you put points on. Loops back to offense every 7 levels.
PICK CAREFULLY: currently there’s no reset mechanic.
Offense:
Power: 2% bonus power per point, stack indefinitely.
Starting Mana: 1% to all mana per point, up to 50%.
Damage Bonus: 0.2% increased damage dealt per point, up to 10%.
Defense:
Vitality: 2% bonus vitality per point, stack indefinitely.
Armor: 5% bonus armor per point, up to 250%.
Resistance: 5% bonus resistance per point, up to 250%.
Ice Magic:
Ice Mastery: 2% bonus ice mastery per point, stack indefinitely.
Block: 1% bonus block per point, up to 50%.
Health Bonus: 0.2% extra health per point, up to 10%.
Poison Magic:
Poison Mastery: 2% bonus poison mastery per point, stack indefinitely.
Critical Hit Chance: 0.1% bonus critical chance per point, up to 5%.
Critical Hit Damage: 1% bonus critical damage per point, up to 50%.
Fire Magic:
Fire Mastery: 2% bonus fire mastery per point, stack indefinitely.
Elite Damage Bonus: 0.2% elite damage bonus per point, up to 10%.
Elite Damage Protection: 0.2% elite damage protection per point, up to 10%.
Light Magic:
Light Mastery: 2% bonus light mastery per point, stack indefinitely.
Healing Bonus: 1% healing bonus per point, up to 50%.
Coin Bonus: 0.2% coin bonus per point, up to 10%.
Dark Magic:
Dark Mastery: 2% bonus dark mastery per point, stack indefinitely.
Melee Resistance: 0.2% melee damage resistance per point, up to 10%.
Missile Resistance: 0.2% missile damage resistance per point, up to 10%.