Wot's da biggest fing you killed, eh? A Marine-boy? Feh. Come talks ta me when ya scores sumfin' with treads!
Tankbustas are an under-used and often overlooked unit in the Ork player's arsenal. Let's break it down.
WS 4, BS 2, S 3, T 4, W 1, I 2, A 2, Ld 7, Sv 6+
Rokkit Launcha 24" range, S 8, AP 3, Assault 1
Right here our first problem with this unit. An Assault 1 gun in the hands of a BS 2 model. Ouch. The offset to this is two-fold. Everyone in the unit has one, and the high Strength/AP of the gun. Tankbustas cost 15 points/model. Keep in mind that a normal Boy with a Rokkit Launcha costs 16.
Tankbusta Bombz are used like Krak grenades with an Armour pen of 2d6+6. Not quite a Melta Bomb, but still better than a Krak grenade.
Furious Charge gives you +1 S, +1 I on the charge. Standard issue for Orks.
Mob Rule allows you to substitute your unit's Ld value for the number of models in the unit. 11 or more is Fearless. Also standard issue for Orks.
Waaagh! means that the Tankbustas can gain Fleet of Foot when the Ork player decides to unleash his Waaagh! Standard issue for Orks.
Bomb-Squigs cost 5 points each, and you can take up to 3 of them in your Tankbustas mob. On a 2+, they will move 18" towards the nearest enemy vehicle, causing an S 8 hit. On a 1, they go after your closest vehicle within 18". These are great. One of the best ways to off-set that horrible Ballistic Skill is to have a few of these around. While shorter range than the Rokkit Launcha, they hit on a 2+! The strength is the same. You know what else is awesome about Bomb-Squigs? According to GW's FAQ, they are unhindered by difficult/impassable terrain and do not require line of sight!
Tankhammers are free, and you can take up to 2 of them in your mob. These are interesting as you trade your ranged weapon for a two handed melee weapon. The good bit is that it is S 10. If you can get into h2h with a vehicle with that, you're golden.
Some of you may have noticed that I still haven't addressed the elephant in the room: Glory Hogs. This part is important, so I saved it for last.
Glory Hogs is the biggest reason a lot of Ork players don't take this unit. Tankbustas must "always shoot at and/or assault an enemy vehicle if there is one in line of sight, regardless of range." Hmm, that "and/or" is a bit vague. Well, according to GW's FAQ, the Tankbustas are free to move as they like in the movement phase. Glory Hogs takes effect in the shooting/assault phase, forcing you to shoot at and attempt to assault an enemy vehicle in LOS.
Glory Hogs can be a fun and fluffy rule, though a wise opponent can use this rule to control and negate your unit. This is why they aren't taken much. Too much chance of losing control. Lets talk about ways that you as an Ork player can work around and overcome this.
Plan your movement. Remember, the movement phase is yours. You get to position your Tankbustas before Glory Hogs takes effect. Don't want to shoot at a vehicle, but rather at the Marine-boys nearby? Position yourself so that no vehicle is in LOS. It takes a lot of strategic thinking, staying ahead of your opponent by a turn or two to keep them away, but it can be done. Also, keep in mind that whatever a Bomb-Squig targets does not affect the target of the Tankbustas unit. You can fire away at who-ever, and still release a squig after a vehicle 18" away even if out of LOS.
Put them in a transport. Maybe you do want them shooting at vehicles, but the problem is that your opponent is kiting them around the board? Staying always out of range yet staying in your line of sight, thus forcing you to waste shots at something way out across the board? Put them in an empty Trukk, or even a Looted Wagon. A Looted Wagon costs 35 points. Keep it Open-Topped, so that all (up to 12) your Tankbustas can shoot. Hell, throw some Big Shootas or Rokkit Launchas on the Wagon to help out... they're cheap. This additional movement will allow you much greater control over your Tankbustas, meaning you'll be within range of that vehicle you want to shoot more often.
I give them a transports so they can be sure theyre in range of any vehicle, using my bigger battlewagons to block their lines of sight. (Scuzgob of Adam's Level 3 Team Project Blog)
Having an entire mob of Boys with S 8, AP 3 guns can be a very powerful tool. Having savvy uses for this underestimated unit can really put the hurt on your opponent.
The_King_Elessar (of Mind War, FTW!) brought up a good point about Tankbustas competing for the same Elites slot as Lootas. I would argue that as far as vehicles and Marines go, Tankbustas are better at it. Against mid-armoured troops like Eldar/Tau you'd be better off with the Lootas.
Assuming 10 Tankbustas vs Marines, you're looking at causing 2.5 wounds/round, due mainly to the AP3.
Assuming 10 Lootas (D3 shots, so assuming average shots of 2/model) vs Marines, you're looking at causing 1.5 wounds/round ... because a Deffgun's AP is 4.
Against T4 or lower, the difference in strength won't matter much unless you're shooting at a multiwound T4 model (in which case a Rokkit causes Instant Death). Against vehicles, though ... You'll want the S8 Rokkits over the S7 Deffguns, despite the increased range.
What have your experiences been with Tankbustas? Hit me up in the comments, and I may just add it in the post!