The Mechanicus has their own Heavy Tanks now. The Macrocarid Explorator was originally a class of heavy vehicle used by the Mechanicum during the Great Crusade and Horus Heresy. The term itself was a classification of heavy armored and fully environmentally sealed vehicles used for combat, command, and exploration purposes by a Magos.
Apparently like the Ordinatus, no two Macrocarids were exactly alike, each being a unique vehicle specially and repeatedly redesigned and modified by their masters. In the earliest years of the Crusade however the Land Raider Proteus was the most common type of these vehicles, but as the Imperium expanded wholly unique hulls were added to the Mechanicum armory until the Macrocarid Explorator essentially became its own thing.
The model itself looks like a Triaros on steroids. Using a similar chassis as the Triaros but inflated by several orders of magnitude and much more heavily armored especially in the hull regions. The Macrocarid Explorator has two large treads akin to those of the Sicaran Battle Tank, two forward sponsons with a choice of either two lascannons or two irradiation engines, and either mauler bolt-cannon or a graviton imploder.
The Macrocarid Explorator's model has been released by Forge World and we finally got the damned rules. The best way to think of the Macrocarid Explorator is as a customizable Land Raider. It has transport capacity and it has AV 14 all around coupled with an impressive 4 hull points. This makes it a beast of a vehicle when you want both cover support and assaulting the most heavily defended position short of Titans. The base points cost is actually entirely reasonable and it comes with lascannons on side sponsons, plus a mauler bolt-cannon on the hull. The added rules provide an all round survival quantum, plus other nice rules such as the augury scanner.
Unfortunately, there are few weaknesses that may hinder the Macrocarid. The Macrocarid is a strong choice all round, but like all good choices there is a temptation to splurge a lot of points on the vehicle, causing the price to skyrocket like the price to make a Custodes nowadays in the 41st millennium. This temptation should be resisted, no matter how good things look on paper. A few Destroyer strength hits will take care of this beast and its often better to not have all proverbial eggs in one basket as a result.
Due to the customization available, there are several builds for the Mechanicus Land Raider which can be seen below:
Macrocarid Explorator with Exploratory Augury Web (245 points): Some people like to use the exploratory augury web upgrade for its ability to mess and troll around with reserves. But this comes at the price of a reduced transport capacity. Hence it might be the case that this build is a mobile wall or screen for other pieces of your army and to act as a giant DISTRACTION CARNIFEX.
Macrocarid Explorator with Flare Shield and Armored Ceramite (240 points): A very tough vehicle for any army to fight against and a complete bitch to put down. The combination of the Flare Shield and Armored Ceramite means that shots that would otherwise severely damage the Explorator now has an increased chance in it being deflected. Put your precious robots inside and use them wisely. Add a conversion beamer to further maximize trolling.
Macrocarid Explorator with Two Irradiation Engines and hull-mounted Graviton Imploder (250 points): If you want to really turn your Explorator into a cruel joke of a Tarpit cleanser then accept no substitutes. Irradiate your opponents with your Irradiation Engines and then scatter their remains with the Graviton Imploder. Tyranid and Ork players cry themselves to sleep when this rape machine is put on the table.
Macrocarid Explorator with twin linked Plasma Phased Fusil and sponson Mauler Cannons (205 points): For when you want to penetrate the rear end of every ceramite wearing MEQ on the table. Very nice dakka to give to your power armored playing friend. Expect to lose friendships over this. Only downside is the overall lack of anti-vehicle weaponry so expect to be targeted by almost every tank destroyers on the map.