Defense

Defense Rating: 2.4 rating grants 1 Defense Skill.

Defense Skill is the base unit for level-based Defense, while Defense Rating is additional Defense added through gear.

5 Defense Skill adds one effective level to the calculation, reducing the chance to be hit by a Critical Strike by 0.2% and increasing the chance attackers will Miss you by 0.2%
(This means 1% Miss and -1% crits is achieved by 25 Defense Skill)

Equal level Mobs have a 5% chance to score a Critical hit.

Therefore, 300 additional Defense Rating will reduce the chance of being Critically hit to zero.
This is the equivalent of 475 Defense Skill (70 x 5 is your base, giving 350, plus 300 rating from gear which is equal to 125 Skill. 350+125=475)

Threat Generation

Differences between Rage and Mana threat generation

Q u o t e:
The Paladin uses mana where the other tanks use rage. While this originally prevented them from being viable tanks for long fights, mana regen from healing received (via Spiritual Attunement) makes this no longer an issue. Tanking Paladins affectionately refer to their “Blue Rage bar”, as SA replenishes their mana supply constantly. The remaining functional differences are twofold: first, a paladin has a much larger (and scalable) functional resource pool (i.e. 100 rage is worth X seconds of ability use, 4000 mana will be more time of ability use than X), offset by a greater need for efficient spending. Second, they start a fight at full resource, making heavy frontloading possible.

The Global Cooldown

The Global Cooldown (GCD) is the 1.5 second down-time after casting during which your abilities cycle around and are unavailable. This mechanic prevents super-macros and “mods” or “bot” programs from hyper-spamming abilities in an unbalanced way.

Taunting

[Righteous Defense is a Taunt] ability that defies all regular threat abilities and is regularly used by tanks. It does three things:

Avengers Shield Macro

For those who pull mobs with Avengers Shield, here is a macro that cast avengers shield and notify the party that you’re pulling the mob. Also it prevents spam if you target nothing or a friendly.

Blessing of Sanctuary

I found a good write up on BoS.

Blessing of Sanctuary, the 21-point Talent of the Protection tree, grants the benefit of reducing damage done for each hit by 81.
The damage reduced by Blessing of Sanctuary is factored in before mitigation is applied.
This includes armor, block value for blocked attacks, siphoned damage due to Blessing of Sacrifice, everything.

For example;

Illumination is 60%

The Devs heard enough of the QQ and up’d the percentage from 50% to 60%.

“Illumination“: This talent now only gives 60% of the mana cost of the critical heal. It also now returns the correct amount of mana when used with ranks 4 and 5 of “Holy Shock”.

A RET/PVE Paladin DPS Guide

I found an interesting guide that focuses in excelling as a RET/PVE DPS Paladin in raids.