Its literally Rat+Bomb and ready to go. Here is the latest from Forgeworld this morning.
New from Forgeworld
https://www.forgeworld.co.uk/en-GB/Cawdor-Bomb-Delivery-Rats-2019
Cawdor Bomb Delivery Rats £12
5 Cawdor Bomb Delivery Rats
Deliver explosives right where your opponent least expects it!