In orthank raid, Saruman crafter 5 rings of power.
After players defeated owners in 4 preraids they come to face the Saruman. They climb to the peak of Orthank, and battle him atop the tower. He was thinking that PCs want the power and will join him. However, after raid group claims rings, he sees our true intentions- to destroy his own ring of power.
He summons 5 'clones' that players need to defeat. Each clone is based on different element, as rings and wings of raid (shadow, lightning, fire, frost, poison) and posseses different special attacks. There are 5 phases, after each players must run to their positions and use rings in order, otherwise phase needs to be repeated. Each phase got special conditions and events, theese would be hard to describe to someone who never played lotro.
Anyway, each raid got special optional objective called challenge (great idea BTW, I wish DDO had something like that in raids, its comparable only to optional about defeating LoB thrice before destroying forge). Extra challenge in fight with Saruman, is to never fall victim to any of his special attacks. This is quite hard to achieve, as a single mistake from a single player causes objective to fail, but completing it is very satisfacting and rewarding (in form of extra chest and, for 1st timers, extra barter currency and turbine points).
After 5th phase, Saruman's ring is destroyed, and he pushes players from the pinnacle of orthank.
Fortunately, we're saved by great eagles and delivered to the ground when raid loot awaits.
This raid is considered greater lore break than anything Jackson put in his LotR movies, but its intensivity, difficulty and fun it provides makes up for this.