MURDERWINGS
Chapter Master MURDERWINGS is an ungodly cheesy Raven Guard character that came about as of one of the newer supplements. While he's not the toughest of characters, he is essentially the Space Marine equivalent of an Eversor Assassin. He can also be considered the Killier, less tough cousin of Chapter Master Smashfucker
Warzone Damocles: Kauyon
MURDERWINGS is created when a Raven Guard Chapter Master takes the three artifacts, Swiftstrike and Murder, and Raven's Fury, A relic jump pack. This grants him 6 attacks on the charge, with a special ability called Flurry of Blows, that allows him to roll to attack again for every hit he incurs (inflicts) in melee. That gives him potential for up to 12 attacks on the charge, which is even far greater than the melee potential an Eversor has. You are generally best off attaching him to a barebones squad of Jump-assault marines so as to ablate wounds for him and make sure he gets into melee. A 5-man squad can be used as insurance for when you're hiding him behind a BLOS terrain piece, while a 10-man can get him across the field. Regardless of which squad size you use, MURDERWINGS' sheer killyness will usually ensure that he will kill the enemy so hard, his own assault squad won't even get to participate in the melee. It's not unheard of for MURDERWINGS to slaughter so many enemies on the charge, that neither his own squad, or the enemy squad can make base contact for the fight below his initiative, resulting in an auto-win for MURDERWINGS to sweep the entire remaining squad off the board. He can even solo an entire 300-man green tide doing this and with the right positioning.
His Jump pack also costs the same as a normal jump pack, but gives him an S6 Hammer of Wrath with stikedown, so he might be able to force people to not fight him at his own initiative.
A Raven Skull of Korvaad might be good here, as it ups his WS to 7, making him hit models with WS 4 on 2+ instead of 3+, and if he dies, it buffs your units (most likely Vanguard Veterans) within 6" of his body with Rage and Hatred, all for 15 pennies. Enjoy shredding Marines twice as hard, even in death.
Combining this with the fact that 7th Edition made it so that chapter master's can call an orbital bombardment and still assault, MURDERWINGS has quickly built up a reputation on /tg/ as being the go-to chapter master for Soloing entire hordes of infantry. And unlike SMASHFUCKER, MURDERWINGS is actually pretty affordable for most armies, as he's clocking in at only 200 points with his full panoply. For your shooting, just use his Orbital Bombardment. Since 7th Edition added in a line for the Orbital rule that allows the Chapter Master to assault after firing it. This way you can have an S10 AP1 Large Blast as an assault weapon for your follow-up of 12 S4 AP3 Shred attacks in the charge.
How to beat MURDERWINGS
MURDERWINGS' ultra-high number of attacks makes him a supremely effective hard-counter to hordes of MEQ or GEQ. While he can indeed solo vast hordes of infantry, his melee attacks are only S4 AP3, and so they can be stopped by two key things. Terminator Equivalents can simply laugh at his wounds, as he can only statistically kill 1.8 terminators a turn, while they will proceed to instagib him at S8 during the I1 step. He can also be slowed down considerably by T6 or T7 models, while he outright cannot harm anything T8 and above(short of wasting his only orbital bombardment on it). He can still churn out enough attacks to burn through a carnifex in only 2 turns, but the distraction of a high-toughness target can allow other melee units to come in and pile on the attacks to his semi-squishy 2+/4++ body.
You can also attempt to keep your distance away from him and shoot him to death, or simply not allow him to get the jump on you by avoiding his LOS blockers. Deep striking squads with heavy weapons can also be used to flush him out of his ambush zones, if not outright kill him if he chooses to deploy without ablative wounds.
If you're playing a Green Tide, you can also choose to paradoxically bunch up your boys in preparation for getting charged by him. You will probably eat an orbital bombardment in the process, but having your models closer to the melee can stop MURDERWINGS from chewing you out of combat, and thus sweeping your entire 300-man squad off the board in one go.