You can find the build here. This is the build I use on my own guardian, which some of you have asked about.
Most importantly, this build puts you in a symbiotic relationship with your party. This means for as long as your party is near you, you can tank anything. Because of Altruistic Heal you are able to keep your own hp up with every boon applied to your four party-mates (this is most noticeable with Empower - the staff 4 skill).
I run a full line up of shouts more often than not with a few exceptions (ie harpy fractal). Utilities can be swapped out as needed, but these are the ones I prefer. If I ever need to swap out for Wall of Reflection I usually swap off Retreat. All shouts apply boons which will help keep your own HP up through Altruistic Healing and will cleanse conditions from party mates.
Receive the Light: As the heal skill this can be used on the party and will also clear conditions. It can usually bring a party mate from 25-30% HP back up to full or very near to it if you catch them for the entire duration.
Retreat: I chose it because it has a shorter cool down than "Save Yourselves!" It will also apply aegis/swiftness which can be helpful situationally in addition to clearing conditions.
Stand Your Ground: It also has a short cool down (and removes conditions).
Hold the Line: Short cool down plus condition removal. I like this one for protect and regeneration, which are also situationally helpful. This is one of my favorite skills at Mai Trin.
Feel My Wrath: The cool down on this skill was recently bumped up, but all shouts have a relatively short cool down time and everyone likes quickness anyway. It will also clear conditions.
This build does reflect the PvP style guardian bunker, but traits are, of course, flexible. Naturally if you're not running Wall you can swap Master of Consecrations to something else.
Strength of the Fallen: Lose hp slower when downed and periodically clear conditions. As good as the build is it's not invincible. Unless you're getting beat in the face by the boss then the party should have plenty of time to revive you. This trait also comes in helpful during condition intensive instances.
Strength in Numbers: Allies gain toughness based on your (effective) level. This trait does not stack, so if there is another guardian in the party ask what traits they are using that way one of you can swap for another trait.
Altruistic Healing: Applying boons to allies heals you (81 hp per boon with this specific build). This is, in part, the crux of the build. With a shout like "Hold the Line" that's two boons for four party members and 644 hp that you get back. With a skill like Empower you will apply four stacks of might three times, so for one party member you will gain 243 hp and for all four you will gain 972 hp (plus you get a burst heal at the end of Empower for 2,748 hp - a grand total of 3,720 hp for yourself).
Invigorated Bulwark: "Gain increased healing power for a period of time each time you block an attack while wielding a mace. Stacks up to 10 times. Mace abilities have reduced recharge." This trait can be swapped for Protective Reviver. However, I use the mace trait during Mai Trin.
Honorable Staff: Increases boon duration while wielding staff and reduces the cool downs of staff skills. This helps primarily with Empower, which is a major source of healing to both the party and yourself.
Pure of Voice: Shouts convert conditions to boons and have their cool downs reduced. This is where all of that extra condi cleanse comes from. This trait can be swapped for any of the other grand master traits and I have often considered trying Force of Will in place of Pure of Voice when not in heavy condition situations.
Master of Consecrations: Consecrations last longer and have a reduced cool down. Granted, in the utilities I am running "Retreat!" instead of Wall of Reflection, but this trait can be swapped for another, however I tend to leave it simply because I never have Aegis long enough for Unscathed Contender to work and in most cases Retaliatory Subconscious will not have a chance to activate either.
Absolute Resolution: Activating Virtue of Resolve removes conditions - increased passive effect. This becomes clutch at Mai Trin.
Indomitable Courage: "Activating Virtue of Courage breaks stun and grants stability to nearby allies. Virtue of Courage's passive effect triggers more frequently." At present, this is the only party-wide stun break in the game. This trait can be swapped with Battle Presence, but contrary to what the wiki says, once Virtue of Resolve is used the party no longer gains the passive effect of Battle Presence.
As you can see I use a mix of Cleric and Nomad armor. Originally I was building my guardian for WvW from a previous guild and the commander demanded the guardians wear Nomad (only). At the time that I finished my armor set Nomad armor was hard to get due to needing the recipe to craft it first and no ability to convert stats on armors or weapons. Since I was no longer part of my WvW guild I decided to cover the missing pieces with Cleric gear, which gave me increased healing power while maintaining toughness and providing me with a little more power. The greatest sacrifice of this build is damage.
I use Mercy runes because this also increases my toughness and helps with reviving allies, which is situationally helpful (primarily in higher level fractals). Alternatively, Monk runes (from Ascalon Catacombs) can be used for increased healing power and boon duration.
Staff is a must for this build, but mace/focus can be swapped out for other weapons as needed or preferred. I prefer mace and focus for their blocks. Shield of Wrath (focus 5) is also good while reviving a downed teammate.
My primary choices were Life or Benevolence, but Benevolence came at a higher recommendation for instanced use where the stacks would likely be resetting either due to deaths or to rezoning (like in Fractals). I use Renewal and Water on mace/focus and Benevolence/Water on staff.
I use the Delicious Rice Ball from the last "New Year" and any of the Furious or Bountiful utility buffs will be helpful. At the moment I use Potent Sharpening stones because that's what I have in my inventory. All of the Bountiful utility buffs add +10% to boon duration, but only the Furious Tuning Crystal adds to healing power - the others add to vitality or toughness.
Questions regarding the build and its use can be directed to me here or via in-game mail (Vinesta is the name of one of my characters). I will be happy to explain in more detail to anyone interested.