Beacon of Light

Beacon of Light is a level 19 Holy paladin ability, designed to aid paladins in healing groups of players.

Tips and tactics
Beacon of Light is one of the most important spells for healing paladins. Some uses are listed below:

By far, the most common target of this spell is the tank, since they will be taking the most damage, and therefore will always benefit from it. The paladin then casts heals on the other party members taking damage, which also heals the tank. Keep in mind that only 40% of the heal is transferred, which may not always be enough to keep the tank alive.
 * On the Tank/Offtank

If more than one Paladin is healing, they can place their Beacons on each others' targets (Crossover Beacon).

Alternatively, they can place their Beacons on the same target to reduce the workload on that target significantly (Stacking Beacon).

While this spell won't turn a Paladin into a great group healer, properly executed, Beacon can dramatically improve a Paladin's group healing contributions. There is no single answer for who the target of this spell should be; it will depend on the encounter and the heal assignments.
 * Smart Placement

The heal on the Beaconed target is delayed by about half a second, which can be dangerous in very healing-intensive situations.

Both the casting range and the effect range of Beacon of Light are 60 yards, significantly larger than the normal 40 yards of most healing spells. This gives the Beacon several extra uses.
 * Range

If for some reason you are out of range and are unable to get within normal healing range, you can cast the Beacon on your target and then heal yourself instead, as long as you are within 60 yards of the target.

You can stay farther from the fight using this tactic to avoid AoE or give the tank more time to pull threat off you if you pull too much threat healing.

The effect of Beacon of Light DOES require that you have line of sight (LoS) for BOTH the beacon AND your target. This is a significant concern in fights such as the Sindragosa encounter in Icecrown Citadel, where you are unable to heal a tank while hiding behind a block.

Also note that YOU must be within 60 yards of the target with Beacon of Light if you want them to receive your heals. If you are farther than 60 yards, you CANNOT heal the target with beacon, even if the player with beacon is within 60 yards of someone you are healing.

You must be careful using any of these tactics, if the tank dies or loses threat, it may be difficult for you to heal other party members. Also, being too far away will make it very difficult for the tank to get anything you accidentally pull off of you, if they even realize it's on you.