The Pump Wagon is a unique form of chariot and, by and large, treated in the same way as a chariot in terms of the game. Therefore all the usual rules for chariots apply except as noted below.
The main difference is that, unlike other chariots, the Snotling Pump Wagon's speed is not fixed but is determined randomly each turn to represent the sporadic efforts of its tiny crew. The Pump Wagon is moved during the compulsory part of the player's Movement phase and automatically travels 2D6".
The player has no control over the distance moved, but he can decide which direction to move the Pump Wagon before he rolls the dice. The Snotties steer by leaning from side to side, causing the Pump Wagon to veer in an alarming manner (in case you were wondering!).
If the Pump Wagon should hit an enemy unit then it is treated as having charged into it and is brought to an immediate halt. The target unit can make the usual response just as if it had been charged in the normal manner. If the unit flees then the Pump Wagon continues its movement from that point.
If a Pump Wagon's move takes it into terrain that it cannot cross it is automatically wrecked and destroyed. Its crew are killed, incapacitated, or are overcome by a fit of the giggles and take no further part in the game.
If a Pump Wagon is careless enough to move into a friendly unit then it fights against it just as if the unit were enemy troops. This is unlikely to happen as the player can steer the Pump Wagon even though he has no control over its speed. However, should this occur, the Snotlings are assumed to be far too excited to notice that they are scrunching up fellow greenskins. They will continue to fight until one side is broken or destroyed.
When a Pump Wagon charges into combat it inflicts 2D6 impact hits at its Strength of 4. This is worked out exactly like other chariot impacts and differs only in so far as the number of hits is greater (2D6 as opposed to the usual D6).
The Snotling Pump Wagon is crewed by overexcited Snotlings out of their minds on adrenaline. It is Unbreakable.