This is it. You've defeated Shannox, Beth'tilac, Lord Rhyolith, Baleroc, Alysrazor, and Staghelm. Only Ragnaros, the Lord of Fire remains. Again.
I'm changing things up a bit for this guide. Because this encounter is so complicated, I'll discuss strategy and tips for each phase in turn.
Ragnaros, phase 1 Your raid will be formed in a loose semicircle or U-shape around Ragnaros, who remains immobile throughout the fight. Tanks will be on one end, melee the other, and ranged and healers hang out in the middle.
There are two knockback effects in this phase -- Wrath of Ragnaros, which targets a random player and everyone within 6 yards of him, and Hand of Ragnaros, which targets everyone. You'll want to be aware of your positioning at all times, to avoid an untimely death.