My suggestion is a cunning bard, specialising to be a loremaster. The ability to shift people around a great deal will work nicely with the melee focused group. Jinx Shot and similar abilities could add a nice touch as has been previously stated.
I would build the bard around buying as many of the lore skills as you can and leaving the social skills alone. Then buy Bardic Lore and Bardic Jack of All Trades. This will mean you have +7 to stat for lore skills since you are trained in them and +4 in all untrained skills. You can really put in for the team in situations where you have no idea what skills will be missing at any point.
Alternatively, the Runepriest is at its best in melee heavy groups and can really excel. This would rely on your group working well together and the strikers having spent effort to get lots of movement powers. Personally I prefer the bard though, as Runepriests just don't have the stats to fill in the skill shortage.