Urgoz...

First, this is the most demanding mission in the whole game - getting a good team will need at least 1 hour.
Next, even if you get to see Urgoz, how do u kill him? (Cleaning out his 2 serpent healers is easy.)
Tried the following:
1. Mesmer blackout - no effect.
2. Ranger Distraction Shot - interrupted forest binding but no lasting effect, he just casted forest binding right away!
3. Mellee attacks have nearly no effect on him.
4. Maelstrom doesn't seem to have effect.

So, looks like the only way is to give him massive degen.
Things we have tried:
1. Poison Arrow - yes, get it on him constantly
2. Conjure Nightmare and Phantasm - very difficult for the mesmer
3. Mark of Rodgort - it also works but burning is only 1-3 seconds.
4. Life transfer - also works to some extent.

We did finish him off after like 45 minutes of constant retries. Is there a more efficient build/skills sets to tackle Urgoz?

Sort of sounds like some of those Final Fantasy monsters with 10 million HP.

One question: How could you survive Explosive Growths?

Simple, u just click on the floor away from the growths. If you're knocked down somehow, good bye, rez time.

Dust trap