If you want your focus to be melee, as per your build to date, at least half of your points will be in the Rogue mastery.
To supplement the melee aspect of your character, consider:
- Heart of the Oak for the party hit point buff (if as a group your resists are poor, you could increase the secondary skill Permanence of Stone; the points can be removed as resist gear improves).
- The Strength of the Pack buff is very nice as it adds Total Speed along with a lot of damage and a little armor... because this buff line is pet based, you need at least one point in each prior skill. I'd probably go Call of the Wild (7 or 8 points for the 2nd wolf), Maul (as many points as you can spare to give the wolves some punch), Survival Instinct (one point only, to unlock Strength of the Pack) and then max the Strength of the Pack.
- Regrowth and its secondary skills can be nice. A single target heal on whoever is taking damage plus secondary heals to those allies in the near vicinity. Accelerated Healing is ok, but the refresh on Regrowth is fairly short already, so focus more on Regrowth and Dissemination if you go this route.
- Refresh is something to look at (Strength of the Pack puts you 24 points into Nature, and this is a 32 point skill). I'm not sure which skills with lengthy recast timers your party uses. In its current 1.20 form, its not nearly as powerful as it was, but Refresh still helps a bit. For every skill point spent (up to 12 ranks) it reduces the remaining cooldown by 6 seconds (might be 8, but I think its 6). Itself on a 10 second timer, if you were to click Refresh every 10 seconds for 30 seconds (and had 10 ranks), skills would be available 3 minutes earlier then normal. Even with just a few points into Refresh, short reuse timer skills like Quick Recovery or Lethal Strike can be used back to back virtually immediately.
If you were playing single player, I'd strongly recommend looking at Plague in the nature tree, as rogue lacks AoE's... but with two other players in your party, you don't need an AoE as much.
In the rogue tree, you'll probably be going with Weapon (Spear) and Shield, taking skills like Blade Honing, Nightshade (secondary of Envenom Weapon), either or both Lethal Strike/Calculated Strike and secondaries, Open Wound, Anatomy. I personally didn't like traps but many players find them useful. Throwing Knife can be a good skill, especially as it can apply your poisons and the useful Nightshade debuff to several opponents at once. If you take Refresh from Nature, Lethal Strike is probably more valuable then Calculated Strike, but otherwise its refresh is a little slow and you'll want points into both skills.
Hope this helps you a little.