Here is a tanking Crusader build: Fire Wall
http://us.battle.net/d3/en/calculator/crusader#aZSdfi!YUhV!acZcYa
This build raises all defenses and punishes those who want to pass through them. With this spec, the Block is like its Hot (block 100,000 damage in 10 seconds) achievement popped on the 1st group of mobs (at level 64) within about 3-5 sec (had a level 60 shield so it only stopped a maximum of about 4,000 per hit). The best part, is right when that achievement popped, all of the enemies were dead, due to Punish-Roar. This causes all blocks to deal 45% weapon damage as fire to all enemies within 15 yards.
This is one of the main AoE damage methods of this build, but it has several more tricks up its sleeve. Whether enemies are up close and personal or are a fair distance away, and group of enemies fall quickly to Blessed Shield-Combust, due to its 33% chance to cause a fiery explosion on its original target and its 3 ricochet victims. Plus, if you have recently hit something (doesn’t have to be an enemy) your Punish effect increases your block chance, which further increases the damage of your Blessed Shield. Then, if you want to close the gap between you and that group, or just have a single target, Shield Bash will be your next choice skill (which also gains more damage from having an increased block chance) since it deals 550% weapon damage.
Then, for massive groups Condemn and Provoke will be vital. Condemn will bring all enemies closer to you over a span of 2 or 3 seconds. During this time, it gives you enough of a chance to use Punish and Blessed Shield on a couple of enemies, increasing your block chance and dealing high AoE damage. Follow this up with Provoke, to replenish your Wrath and give you a further 50% chance to block for 4 seconds, and then finish them off with more Blessed Shields and/or Shield Bash.
The Passive skills are designed to help you in survival and to dole out more damage. Righteousness will allow you to gain more wrath as well as store more of it to cast your devastating abilities. Hold your Ground removes your chance to dodge, which is usually low as a Crusader anyway, and increases your chance to block by 15% (also increases the damage of Shield Bash and Blessed Shield). Renewal will help to regain any life lost or even top you off depending in some scenarios. Lastly, Divine Fortress increase your armor by a percentage equal to your block chance.
I do know that a lot of Crusaders out there like to use the Heavenly Strength passive, allowing them to use a two handed weapon and their shield. I am one of them too and I have already thought of this. Simply switch out Divine Fortress for your Heavenly Strength (provided your are level 70 of course) so that way the blocking mechanic is still your key to success. If you are not level 70 this still is not a problem though; if you are too low level, then you will want your choices to be Righteousness, Hold your Ground, and Heavenly Strength.
I hope you enjoy this spec! And if you have a certain class that you’d like helping in making your build, or want to find a certain way to make abilities work together, just leave a message in a Comments section, and I will help you in whatever way that I can. Until next time!