If this is HM all bets are off.
But for NM, with the proviso that I don't actually play a ranger, here's a team based on my experience as warrior/necro/rit...
1. Player ranger with Barrage, Ebon Standard of Honor, Tryptophan Signet, whatever else you like.
2. DPS channeling/blocking Rit. 12+1+3 Channeling, 12 Spawning Power. Splinter Weapon, Signet of Spirits, Bloodsong, Agony, Ancestors' Rage, Spirit Burn, Spirit Siphon, Essence Strike.
3. Minion bomber and prot necro. 12+1+3 Death Magic, 9 Soul Reaping, 9 Protection Prayers. Aura of the Lich, Animate Bone Minions, Death Nova, Masochism, Putrid Bile, Aegis, Protective Spirit, Shield of Absorption.
4. Panic Mesmer. 12+1+3 Domination, 9+1 Fast Casting, 9+1 Inspiration. Panic, Mistrust, Cry of Frustration, Wastrel's Demise, Power Drain, Leech Signet, Channeling, hard res from secondary profession. [I don't normally trust heroes to run Wastrel's, but with so many foes Channeling should give them more energy than usual.]
5. Fire nuker ele. 12+1+3 Fire Magic, 12+1 Energy Storage. Mind Blast, Liquid Flame, Mark of Rodgort, Rodgort's Invocation, Glowing Gaze, Fire Attunement, Glyph of Elemental Power, hard res from secondary profession.
6. Heal and prot rit. 12+1+3 Restoration, 10+1 Spawning power, 8 Protection Prayers. Spirit Channeling, Recuperation, Life, Protective Was Kaolai, Mend Body and Soul, Spirit Light, Aegis, Shield of Absorption. [Recuperation is a 25e beast but it affects allies, including your minions and the shining blades. Disable and micro it so it's timed/placed right.]
I left off my usual SoGM rit because it's a single target build and this is an AoE fight.
All the AoE is non-scattering, to keep things bunched in the overlapping AoE.
Set the healer to avoid combat and the rest to guard.