ArenaNet Dev, Eric Flannum, recently elaborated on Explorable mode in a series of posts over at GuildWars2Guru.com. Here is what he had to say:
Players could make a build that resembles the trinity but it could never truly be the trinity. You cannot for example make a dedicated healer no matter how much you pump into your support trait lines. When you start getting to tougher encounters no matter how much armor and health you have you will never be able to stand toe to toe for long against most of the foes you’ll face. Because of this even a 5 person group that has 3 dps focused characters, a support focused character, and a damage soaking character (which is a standard trinity setup) will not play anything like a standard trinity group. If those players insisted on playing like a standard trinity group they could succeed against the easier content in the game but probably couldn’t finish a story mode dungeon let alone an explorable dungeon or some of the tougher events in the game.
To go a little bit more in depth with the answer I gave, it doesn’t really matter which professions you bring. Over the beta weekend I played through the dungeon with several different journalists and getting through was never a matter of bringing particular professions or even changing the builds that people were using. When we hit a tough patch people would change which weapons or utilities they were using but nobody ever had to go respec their traits. I was in groups that wiped multiple times in story mode but I was also in groups that did not wipe at all in story mode and was in one group that made it through explorable mode (we wiped a lot in that one). It all came down to how well we coordinated and how well we responded to the situations we encountered.
For example, in the explorable run through I think it was two journalists who were both warriors (one may have been a guardian, I’m having trouble recalling), our producer Chris Whiteside with a ranger, Izzy playing an elementalist, and myself playing an engineer. At different times Izzy was our condition removal guy, our debuffer, and our “tank” (bait is a more appropriate term actually). He was our most important player because he was our best player but he was actually very support/healing specced. The important thing about that group was that we were all talking and coordinating our efforts and coming up with strategies together. Those strategies never really revolved around specific skills but rather things like “We need condition removal” or “we need to stack as much vulnerability on this guy as possible” or even “we need Izzy to run around attracting attention while the rest of us activate the traps built into the area to kill the hordes of incoming mobs”. I hope that helps shed some light on how the game plays.
This series of posts shows yet again why GW2 will be setting the standards in online gaming once it launches. Repurposing a dungeon after the initial run through complete with changing the strategy and difficulty - yeah, that is boss. No pun intended.