Manticore Launcher Tank
The Manticore Launcher Tank is one of the most subtle options the Imperial Guard has, being able to deliver as much firepower as an entire Basilisk battery from a single unassuming vehicle. It is built on the versatile Chimera chassis, with a Manticore Missile Launcher attached to its back.
The main reasons that the Manticore isn't more widely used are that it is difficult to load (so it is extremely vulnerable once its missiles are all launched) and a finicky machine to operate -- the machine spirits of the tracking, guidance, and launch systems are as temperamental as they are advanced. As such, they are limited in deployment to artillery regiments for the most part, as they are furthest from the front lines and most likely to have the tech-priest expertise required to maintain them.
The Manticore's Storm Eagle rocket is a thing of delight at 2d6 S10 AP -2 causing d3 wounds each. Like the Wyvern and Basilisk, it benefits not only from indirect fire, but also from the master of ordnance's +1 to hit boost. A single manticore is a genuine threat to a huge number of targets, and remarkably doesn't break the bank at 125 pts + upgrades (135 pts base post Chapter Approved). The only downside is its limited ammunition, and perhaps less than stellar AP.
Like a number of New Guard munitions, the Manticore is a strong all purpose attacker causing ladles of grief to anything. The Manticore will routinely earn its points back in with its opening salvo.
The limited ammunition and randomness of each salvo make the Manticore perhaps less reliable for anti-infantry duty than, say, a Leman Russ Punisher, but it's not unheard of for a battery of Manticores to destroy the bulk of an enemy's forces in the first or second turn with a lucky dice roll or two. Expect the enemy to focus everything on its destruction, even to the exclusion of all else, and make sure that he doesn't get there.
A player in a major tournament in New York managed to pull off several bits of undiluted win when using Creed to Scout Manticores against Ork players, enabling them to perfectly get line-of-sight with the enemy army and fire off a barrage. This is widely considered cheese, but remains absolutely hilarious and is something that needs to be witnessed, if only once.
The Rebellion Begins
Due to the Manticore being an insanely overpriced model - even by the staggering standards of Games Workshop's notorious tendency to charge an arm, leg, and testicle for its miniatures - players have resorted to increasingly-clever methods for representing Manticores on the tabletop, the most common way being to either mod a Chimera APC, which costs about half as much, or to go the full Monty and using decidedly non-Games-Workshop miniatures in order to represent them on the tabletop. Considerable amusement and much rage from certain Neckbeards have ensued.
Some of the more infamous ones are shown below.
One of many mods of a Chimera. This one weds a rocket pod from a toy MLRS to a Chimera chassis. It works.
A fairly clever Manticore made from a Chimera and a Whirlwind.