The Paladin combat system is based mainly on four elements: aura, blessings, seals and judgements. Combining efficiently these elements a paladin can face efficiently quite every situation.

Auras affect all the group member within 30 yds from the paladin, costs no mana and the effect is permanent (till the paladin dies). Multiple paladins can use different Auras within a group. If multiple paladins in a group have the same aura, effects don’t stack.

Blessings are spell buff that paladins can cast on themselves or any friendly target. Some blessing are limited to party/raid members. Players may only have one Blessing on them per Paladin at any time. When more than one paladin is present, talk with your others fellow, in order to plan a better buff coverage for every group / raid member. Blessing are considered magic effects so can be dispelled.

Seals are short-term self-buffs with a wide range of effects. This means obviously that every paladin can have only one seal active at every time. They can buff paladin power, enhance regeneration and a lot more. All seals lasts 30 seconds. Seals are considered magic effects so can be dispelled.

When a seal is active you can judge it via the judgement ability. The seal effect will stop immediately and a judgement effect is unleashed on the enemy target. You need to be in a 10 yards range from target to judge a seal. The judgement ability has a 10 seconds cooldown (8 with a talent in retribution tree). In other words if you have a seal active on you, with judgement you stop its effect and activate a judgement with the same name as the seal on your target (i.e. Seal of Light, judged, become Judgement of Light).
The judgement ability mana cost is 90 (79 if you have benediction talent in retribution tree).

Judgements are short range spells that affects your target. There are 2 kind of judgements from 1.9 patch:
 

• judgements that do direct holy damage on target. Effect is istant and can’t be obviously dispelled. These are judgement of command and judgement of Righteousness.
  
   
• judgement that places a magical debuff on your enemy target (visible as icon) with various effects. The debuff duration is 10 seconds, however every time you hit judged enemy target with a melee swing, timer is reset so, if you keep fighting, it’s possible to have an everlasting judgement effect. These judgement are: judgement of the crusader, judgement of justice, judgement of wisdom, judgement of light. Judgement of this kind are considered magical debuff and can be dispelled. Judgements, if activated on the same target from different paladins, don’t stack.