There is a very simple tactic that can be used with a Skaven Engineer. Look, I will admit it, it makes me feel a little dirty, and no, I am the first to admit it, I learnt about it by reading a forum, not by careful study. However after being mind-razoured more times than I can count, it is time to embrace the cheese..
The play works like this...
Equip a Skaven Warlock Engineer with a doomrocket. It will cost you only 45 points!
Start him within 12" of a Grey Seer.
Turn one, use the skitterleap spell to place the Rocket carrier to the side of the Enemy's line and fire using only 4 dice. The rocket will go 14" almost every time, drops a large template which causes S5 hits. It will pay for itself almost every time and almost never misfires!
The rules ask that my figures are wysiwyg as much as possible and so to counteract the cheese, I thought I would make the figure as obvious as possible.
To achieve this I took a clan rat with spear and added a rocket from the crew of the Empire Helstorm rocket battery. I added a small length of guitar wire as a fuse and fixed a torch from the Empire flagellant set with the end of a paperclip. There you have it, one Engineer with rocket.
The lit rat comes from the IoB warpfire thrower.
The lit fuse was enhanced by two pieces of static grass fixed to the end to represent the light. Bit of a happy accident, but goes OK. Hope you enjoy...