Hello,
I also made a AoE Guardian, this is my build.
http://www.gw2db.com/skills/calc/guardian#7|0|3527|3980|2445|3407|4225|30|906|2409|2291|0|0|0|0|0|0|0|0|30|880|1403|1400|10|2286|0|0|0|0|1|0|0|0|0|0|0|0|0|0|0|0|0|0|
My armor and accessories are based on Power and Condition damage.
The way I kill: I lure some monsters and pull them all towards me, I pop my Symbol of Wrath and Purging Flames to put them all on fire, then a Leap Of Faith so I get a flame around me which burns nearby enemies(remember I have the trait which gives me 10% extra damage vs burning foes) then a Whirling Wrath and finish them off with auto attack so my skills have no cooldown for the next group.
Every 5th attack burns a foe also thanks to the virtue, so the 10% extra damage vs burning foes from the trait is really nice in my opinion!
Hope you may get something out of this. ^^