Doomwheel

Doomwheel is a Skaven war machine unit in Total War: Warhammer II. Careening across the battlefield, smashing everything on contact and incinerating anything too close with bolts of savage Warpstone lightning.

Description
Few devices sum up the blend of science and sorcery, the sheer inhuman ingenuity of the Skaven, than the infernal war machine known as the Doomwheel. At first sight the Doomwheel might seem an oddity, perhaps even comical to opponents that have not faced one before. The Dwarfs, who have suffered many wars against the Skaven, know full well the Doomwheel's measure and will direct every war machine at their disposal to blast the deadly wheel apart before it can churn close enough to pulverise the Dwarf battlelines. Indeed, Dwarf cannons will allow themselves to be overrun by the foe, willingly sacrificing themselves for their Hold in order to get off a single shot at the infernal Skaven device. When it works correctly, the Doomwheel whirs quickly across the battlefield, moving more swiftly than galloping horses. If it is going exceptionally well, the Warlock Engineer will even steer the great wheel towards the enemy. This is ideal, as the powerful Warp-lightning bolts fire out, blasting the nearest thing to shrivelled blackness, so it is best to be nearer the foe!

Strategy
The Doomwheel is a literal terror of a unit. It provides a mobile terror causing chariot that has high armor and hits decently hard. It also has missile attacks which allow it to randomly blast units. While you may not think it, the Doomwheel is a strong anchor piece to a Skaven army. It is the closest thing Skaven have to cavalry, it is immune to fear/terror, it has high armour. All of this makes it very difficult to bring down and it can wreak havoc among infantry while Skaven missile/artillery pieces shred the rest of the army.