The Bonecrusher is one of the only Kickstarter exclusive classes in Massive Darkness. This might lead you to believe it was an after thought, or not very well balanced, but that couldn't be further from the truth. In fact the Bonecrusher is a solid melee damage dealer with the ability to "off tank". His role is similar to the Pit Fighter or Shadow Barbarian. For those that didn't back the MD KS you can luckily download the class sheet for the Bonecrusher at CMON's website.
The first skill I generally go for with the Bonecrusher is Mace and Hammer. If you choose the starting Mace, this will give you 2 yellow dice with -1 shield to defenders right away. That can be very potent at level 1. The level 3 version of Mace and Hammer gives you more flexibility by allowing you to choose the additional dice you want, while also removing the best defense dice the defender's roll.
This is an extremely powerful combo, but just be aware that maces and hammers can be somewhat difficult to come by. Between all levels there are only 9 total, and that includes the starting Mace. Also be aware there are only 6 one handed mace/hammers, and 3 that are two handed. Luckily you only need to have a single one hander equipped to take advantage of the skill. This means you can equip anything you wish in your other hand. Because Mace and Hammer is potent you can often sacrifice having a weapon a level or two behind your current level just to gain the benefits from it.
The next skill I generally go for is Charge. This is a pretty standard melee ability and available on most other melee classes. The level 1 version allows you to move and attack with a single action so you won't have to waste an action moving into position. The level 3 version is where things start getting interesting and you gain +2 wounds when you Charge. Finally the level 5 version bumps that up to +3 wounds. Most of the other melee classes just get extra swords from their Charge, but with the Bonecrusher you will be doing automatic wounds which is always great. On top of that you will be maximizing your actions and not wasting them moving into position, as I mentioned before, so that is always nice.
At this point I generally go for the last offensive skill which is Massive Darkness. At level 2 you gain an automatic +1 sword in Shadow Mode. You also have the potential to gain +2 swords if you roll a bam, which is always nice. The level 4 versions gives you almost double that number by giving +2 automatic swords and +3 swords on a bam. Since the Bonecrusher doesn't have a ton of skills that make use bams, this is a good choice for using them up.
That just leaves the tankier abilities; Enhance Health, Fearsome Presence, and Concussion. Depending on your group set up you may want to go for these skills first. However, I do not feel the Bonecrusher is the best tank out there. The dedicated tanks which are the Paladin and Noble Warrior do it much better. I also feel like the Barbarian is slightly better with his higher starting health, higher regen amount, and with Sustain Damage giving him great defense dice(without needing any armor equipped). Depending on your hero choice, Lil' Ned's Shadow Mode skill also is counter productive when trying to tank, as is the Bonecrusher Signature Skill, Blind Fury. More on those later though. If you need to tank in a pinch, the Bonecrusher IS perfectly capable.
The first tank skill I generally go for with the Bonecrusher is Enhance Health. You can get the first version at level 1 which is always nice. You can get the second version right after that at level 2, maxing out your health at 7 and giving an additional +1 regeneration. Finally at level 4 you can get the last version of Enhance Health which gives you a total of 7 hp and 2 regen. I go for this skill before Fearsome Presence because all FP does at level 1 is provide you with Taunt. With no other defensive abilities you are not tanking any better than anyone else though. It's not until you get Enhance Health, later versions of Fearsome Presence, or a shield until you start becoming a more capable tank.
Speaking of later versions of Fearsome Presence, the next version is available early on at level 2. This gives attackers -1 attack dice. This is the equivalent of -1.5 swords, on average. The fourth version of Fearsome Presence gives Taunt and ups the number of removed attack dice to -2. This is the average equivalent of -3 swords. That's not quite as good as the +4 shields the Noble Warrior and Paladin can get so it's easy to see why those classes are better tanks. Lastly there is Concussion which, while it may not seem like much of a tank ability, helps mitigate damage from counter-attacks. With 2 bams you can stun an enemy with the level 2 version and the level 4 version lets you stun them with a single bam. The level 4 version of Concussion also lets you stun ALL enemies in your zone, as well as adjacent zones if you get a bam and diamond. Since the Bonecrusher has no other class skills that use diamonds, this makes good use of them.
That brings us to the Signature Skill Blind Fury, and the Free Class Skill First Blood. Blind Fury is a double edged sword and one of the reasons I don't view the Bonecrusher as a top tier tank. It gives you +1 sword when you attack, but at the expense of -1 shield when you are defending. As for First Blood, it is useful for doing an initial wound when you enter an enemy's zone, or they enter yours. After that initial damage though, you generally won't get any use out of it until the next enemy. Still, it's great for some small damage up front.
When it comes to recommended heroes the Bonecrusher class is pretty limited. Unlike other classes that have two heroes, Lil' Ned is the only recommended one for the Bonecrusher. As I mentioned before his Shadow Mode skill further limits the Bonecrusher's tanking ability by giving another -1 shield when you defend. Combined with Blind Fury that is -2 shields, or 1 blue and 1 green dice worth of shields on average. His Shadow Mode skill does give +2 swords on a bam roll however, so it is decent for offense. That can definitely be useful for pumping out a little extra damage, but conflicts with the skill Massive Darkness which does the same thing (and gives more swords with the second version). If you manage to get 2 bams that can be an extra 4 or 5 swords though.
Lil' Ned's Special Skill "Huge" grants 0-1 range with melee actions. This can be useful for attacking enemies just barely out of your range. For instance when you open a door and a mob spawns in the first room, you won't have to waste an additional action moving in normal melee range to attack. If you are not tanking you also can use it to stay out of counter-attack range of melee enemies while the tank in your party pins the enemy down. Additionally Huge can help give you some flexibility when you want to attack from the shadows. Once you get Charge th 0-1 melee range of Huge becomes much less useful though. You will want to Charge into the same zone as enemies to gain the extra wounds it grants on your initial attack, thereby nullifying the extra melee range.
As a tank the 0-1 melee range of Huge is much less beneficial. That's where the other part comes in. It makes Lil' Ned block line of sight for enemies. This can be an amazing tank ability for other range and magic classes in your party. They can still shoot at range enemies with their combat actions, but the enemies cannot shoot back as long as Lil' Ned is in the way. This is one of the only abilities in the game that can prevent range enemies from counter-attacking your range and magic users.
Since Lil- Ned is the only recommended hero outside the crossover pack, I think it's worth mentioning Samson from the Zombicide: Black Plague crossover. His Shadow Mode skill is pretty limited as you need 2 bams to kill a single minion. Usually you will be better off spending the bams on the Massive Darkness skill. His Special Skill Stout is great for defense though. No longer do you need to worry about the -1 shield from Lil' Ned's Shadow Mode skill. Instead you gain an automatic +1 shield at all times.
As for weapons, Lil' Ned will generally want at least one hammer or mace equipped at all times to take advantage of his Mace and Hammer skill. All are relatively good choices save the level 3 Ice Mace. Having Concussion makes this weapon redundant unless you do not get that skill, or have the lower level version of it. In which case the bam to stun can be decent. Other weapons like the War Mace and Meteor Hammer can be great two handed options. The Meteor Hammer at level 5 in particular is nice because it makes use of diamonds, which aren't used as much by the Bonecrusher's skills. It also allows you to get rid of the best dice a defender rolls if you get a diamond. The level Hammer is not as good because it requires 2 bams to activate the -4 defense to defenders. You are better off using those bams for the Bonecrusher's Shadow Mode skills which can grant up to 5 additional swords. It still has it's uses though if you are not in the shadows.
If you are going the dual wield route the level 3 Light Mace and the level 2 Hammer are decent. The Light mace is nice because it doesn't use any bams, which you will be using in Shadow Mode, and instead lets you re-roll your attack if you do not wound the enemy. Just be careful as this skill will be useless when used in conjunction with later levels of Charge that do automatic wounds. The best one hand option is probably the King's Mace. If you can get the King's Crown and Armor with it you can max out on yellow dice all the while giving defenders -3 shield. Combined with level 3 Mace and Hammer and a one handed weapon that gives 1 red die means you will be just 1 red die short of rolling max offensive dice. This is at level 3. It takes most classes level 5 to achieve this. By level 4 you can combine it with the Fire Sword to max out on offense dice and be doing +9 swords from your Shadow Mode skills and bams/diamonds.