dnd4

Your defenses are your ability to protect yourself against various types of attacks, such as goblin swinging a sword at you or a wizard casting fireball. Different defenses will protect you from different attacks. Each of your defense scores follow the following formula:

10 + (half your level) + (armor or shield bonuses if applicable) + (ability modifiers) + (feat, race, untyped, etc bonuses)

There are 4 defenses:

When an attacker makes an attack roll, it must equal or beat the targeted defense to qualify as a hit. Some powers take effect on a miss too, though with limited potency.

Feats

Feat Requirement Benefit
Agile Command Warlord, Int 15, Skirmishing Presence class feature, level 11+ Any ally that starts their turn adjacent to you gains a feat bonus to AC and Reflex against opportunity attacks
Armored Warrenguard Gnome You do not suffer the normal speed penalty incurred by chainmail and scale, and gain +1 bonus to AC from Large or larger enemies.
Brawler Guard Fighter, Brawler Style +1 Shield bonus to AC and Reflex when one hand is free
Dodge Giants Dwarf +1 to AC and Reflex against attacks of Large or larger foes
Elusive Movement Ranger or Rogue, level 11+ +1 AC and Reflex if you moved at least 3 squares
Evasive Footwork Rogue, Dex 17, Cha 15 +1 to AC and Reflex when you shift 2 or more squares
Frozen Soul Constitution 13 or Wisdom 13 +1/+2/+3 Will Defense, Resist 5/10/15 cold
Great Fortitude - +2/+3/+4 Fortitude
Hafted Defense - +1 AC and Reflex while wielding polearm or staff in two hands
Human Soul Human, Revenant +1 to Fortitude, Reflex, Will
Improved Defenses - +1/+2/+3 to Fortitude, Reflex and Will
Improved Staff of Defense Wizard, Staff of Defense class feature, Con 13, Dex 13, level 11+ While wielding a staff, gain +1 Fortitude, Reflex, and Will
Iron Will - +2/+3/+4 feat bonus per tier Will defense
Last Legion Officer - Ally can shift 1 sq. or gain +2 to AC and Reflex until the start of their next turn when you target them with a power that lets them spend a Healing surge
Lightning Reflexes -, (was level 11+ initially, see feat page) +2/+3/+4 feat bonus per tier to Reflex
Nimble Runner - +2 Reflex when running, don't grant combat advantage when running
Rod Expertise - +1 to attack rolls, AC and Reflex when holding a Rod
Shield Defense Wis 13, Fighter +1 AC and Reflex when a power requiring a shield hits
Shield of Darkness Drow +2 to Reflex while within your Cloud of darkness
Shield Specialization Shield Proficiency (Heavy or Light), Dex 15, level 11+ +1 to AC and Reflex when using a shield
Small Warrior's Defense Fighter, Small size +2 to AC and Reflex when you hold a versatile weapon with both hands
Snowdown Courier Moonshae Isles regional benefit +2 to AC and Reflex against Opportunity Attacks when you run; +2 to Streetwise
Superior Fortitude Strength 15 or Constitution 15 +2/+3/+4 Fortitude defense, Resist 3/6/9 to ongoing damage
Superior Reflexes Dexterity 15 or Intelligence 15 +2/+3/+4 Reflex defense, gain combat advantage against all enemies during first turn of encounter.
Superior Will Wisdom 15 or Charisma 15 +2/+3/+4 Will defense, make saves against Dazed or stunned condition
Two-Weapon Defense Dex 13, Two-Weapon Fighting +1 to AC and Reflex while holding a weapon in each hand