Macharius Heavy Tank
The Macharius Heavy Tank is a family of heavy tanks employed by the Imperium of Man, named for Lord Solar Macharius, one of the Imperium's finest generals. The pattern itself is actually much older.
It is part of a class of tanks known as "second-generation Baneblades" -- since the Adeptus Mechanicus keeps a very tight hold on the Baneblade STC patterns, supply is extremely limited. Other Forge Worlds try to fill the gap in super-heavy tank demand by building heavy tanks of the Macharius and Malcador families. Though it is less durable and possesses less firepower than the Baneblade, it is also substantially less expensive (in the fluff) and more common. Since General Vance Motherfucking Stubbs discovered that large quantities of Baneblades are prone to going missing, armies that needs lots of tanks (e.g. the Death Korps of Krieg) tend to use tanks like these.
In appearance and operation, the Macharius is the big brother of the Leman Russ Battle Tank -- each of the main weapons available to the Macharius chassis is the equivalent of one of the Russ variants. The options for the sponson- and pintle-mounted weapons are also similar.
As is common in WH40K, the fluff does not equal the crunch. In terms of price efficiency, the Macharius class heavy tanks does have difficulty competing with its Leman Russ counterparts in terms of sheer utility. While having twin-linked main weaponry is appealing, without a Heavy 2 buff or twin-linked sponson weapons or a modest price reduction, the Macharius class tanks leave much to be desired. That said, twin-linked weapons alone have stolen victory from the jaws of defeat on more than on a few occasions so the call is yours.
Macharius Heavy Tank
The equivalent of the default Leman Russ Battle Tank; its Battle Cannon comes with a larger blast, as well as being TWIN-LINKED.
Macharius Vanquisher
The equivalent of the Leman Russ Vanquisher. While the Russ's Vanquisher Cannon is a pure tank hunter (no blast), the Macharius carries a second set of shells that have no extra armor-piercing effect but do have a 7" Blast. Not to mention that the Macharius's Vanquishers are TWIN LINKED.
Macharius Vulcan
For when you need to say 2s to kill to space marines. With 30 dice.
Where the Leman Russ Punisher uses non-armor-piercing autogun shells, the Macharius Vulcan mounts the massive Vulcan Mega Bolter, normally a Titan-mounted weapon. Can fire its Vulcan Mega Bolter twice at the same target if the tank does not move. That's 30 shots at S6 AP3, and you're always going to be in range at 60".
Macharius Omega
You thought the Leman Russ Executioner's Plasma Cannon was bad? The Omega mounts an even bigger gun -- it can fire like the Executioner's gun with a longer range and larger blast, or it can fire a single "Maximal" blast with even more range, an even bigger blast, and the strength of a Lascannon. It also has the risk of suffering a Meltdown if it shoots that way (similar to Gets Hot but with D3 lost hullpoints). Apply Trojan and Enginseer to prevent catastrophic self-destruction.
What's next?
Considering that Games Workshop seems intent on making the Macharius tank as a compromise between the Leman Russ and the Baneblade, it is worth wondering what new patterns might yet be released. Particularly in light of the new daemon engines that Chaos are getting and the half-ass Baneblades that the SM are getting ret-conned into their arsenals, the IG might need some balancing firepower. Might a Siege Macharius with extra armor standard with heavy flamer/multi-melta sponsons and twin linked demolisher cannons or a heavy anti-aircraft tank with ten twin-linked autocannons be around the corner? Or maybe Forge World will finally give us a model for the mythical Dominus. Because who doesn't love 3 s10 ap3 5" marine-nomming blasts? Stay tuned...