These themes are meant to enhance the combat roles of a character. As with all themes, any character can take any theme.
Defender
This theme goes well with backgrounds that give you armor proficiency, and classes that enhance your melee attacks.
Defender's Mark
Starting Feature
On your turn, choose an enemy adjacent to you to mark. The enemy is marked until the end of your next turn. A marked enemy takes a -2 penalty to hit any creature other than you.
Defender's Retribution
Level 2
Once per round, when an enemy that you have marked makes an attack that doesn't include you, you can make a melee attack against them.
Multimark
Level 4
You can mark one more enemy.
Ranged Mark
Level 6
Your mark can affect any enemy within 25 feet.
Ranged Retribution
Level 8
You can use a ranged attack instead of a melee attack when you use Retribution.
Retributive Flurry
Level 10
You can use Retribution twice per round.
Striker
This theme is good with classes that use Dexterity and enhance your melee attacks.
Striker's Advantage
Starting Feature
When you have combat advantage, your attacks deal 3 extra damage to the target.
Striker's Feint
Level 2
You can use your action to gain combat advantage against one enemy within 25 feet.
Surprise
Level 4
You have combat advantage against any enemy that has not yet acted.
Quarry
Level 6
One enemy within 25 squares of you is your quarry. Until that enemy dies, it takes 3 extra damage from each attack you make.
Accuracy
Level 8
When attacking you quarry, you can roll the attack twice, and take the higher of the two attack rolls.
Greater Advantage
Level 10
You deal an additional 2 points of damage when you have advantage (total 5).
Leader
Recovery
Starting Feature
On you turn, you recharge an ally's second wind.
Inspire
Level 2
When you recharge an ally's second wind, you can activate it for them, giving them its benefits on your turn.
Motivate
Level 4
When you recharge an ally's second wind, you can move them into or out of melee.
Alert
Level 6
Once per short rest, you may turn a hit on an ally into a miss.
Save
Level 8
Once per short rest, you may turn a failed saving throw into a success.
Energize
Level 10
Once per short rest, you may turn a missed attack into a hit.