Killin' a... Bone... angel... demon... thing. With wings (Lord Marrowgar)

Whelp, after abusing the ever loving Jesus out of random heroics, exploding the first wing of Icecrown Citadel, blowing most of my hard earned gold on 24 slot bags, and getting my first reputation ring from the Ashen Verdict, the main conclusion I've come to is that the normal mode Icecrown bosses are much like the normal mode ToC bosses, and the post-nerf Ulduar easy modes.

But, still, it's a long way before the Lich King's door is open and heroic modes are available, so I'll have something to talk about for a while, starting with Marrowgar. You see Marrowgar the minute you set foot inside, but the path there is longer than you'd think. Traps spawn patrolling giant skeletons with 5 million health, though the bulk of trash itself is not terribly difficult.

The boss himself is also not terribly difficult, but it helps to be aware of the specifics.
Specs
There's no particular spec favorites on the fight, nobody can abuse mechanics to their advantage, but affliction does have one important drawback - the fight includes a periodic threat reset, and the boss is not tauntable. This is manageable, but it does mean you can't do much during part of the fight.

Macros
/target Bone Spike

Simple as that. Marrowgar will impale people on these spikes which must be killed.

The Fight
Most of the fight is tank-and-spank. Kill Marrowgar, switch and target spikes when they come up. Watch the timer for Bone Spike Graveyard, this is the ability that spawns the spikes.

He has two abilities to note: Cold Flame and Bone Storm. Cold Flame sends a line of blue fire towards a target. Just step out of the way and let it pass - it can get quite difficult to find space to stand when he sends out multiple cold flames during bone storm.

Bone Storm is a bit tricky. The boss's hitbox is immense, so keep in mind his whirlwind is also immense. During bone storm, he'll pick a target and race towards them. Move out of the way perpendicularly to his path and get as far away from him as space allows. There is an achievement for perfect dodging on this ability, and it is on the meta. This ability is going to be the Drake killer.

And that's it. Just keep it up, don't be bad, and the loot is yours.

The Profit
The first boss in the zone isn't bad at all for the caster loot, either. There's a bit of everything in this one:

Bone Sentinel's Amulet is probably one of the more notables, a haste/spirit neck. Spirit's a tough stat to come by in icecrown DPS gear, savor it.

Crushing Coldwraith Belt is more typical - haste/crit belt with two gem sockets. A strong upgrade from most existing belts.

Frozen Bonespike is the first caster weapon of the zone. Spirit/crit, so not completely idealized, but still, spirit is a commodity in this gear. 741 spellpower's nothing to sneeze at, either.

Loop of the Endless Labyrinth Hit/crit ring. You'll notice a great many rings and necks have gem sockets in Icecrown. That was something reserved for heroic loot in TOC - They really did pull the stops out on this stuff.

For those interested in 10 man, he's not quite as much of a goldmine, but still has some stuff.

Cord of the Patronizing Practitioner, a haste/spirit belt with two gem slots. A solid upgrade from many existing belts.

Cord of the Patronizing Practitioner hit/haste on the first weapon from 10 man ICC. 657 spellpower's not a bad weapon, either, this is an upgrade from many existing weapons. Even 10 man ToGC weapons with gem slots top out at 644 spellpower.