Venom?
The EMP field is even permanent
and relocatable.
Tick is useful, but probably inferior to roach (180'd that I know). It's worth noting that cloaky as a factory is buffed merely by having the option to make ticks even if they are never produced. Opponents have to be worried about walking into tick traps, and this means longer raiding routes, splitting up firepower, wasted time screening etc.
All in all a positive addition to the factory, thought more difficult to use than glaives or zeus for example.