The thing is likely to cause mischief if it escapes
The damage must be foreseeable, not the escape- Rylands v Fletcher
The damage cannot be personal injury- Transco (2003)
The thing itself does not need to be inherently dangerous
If the case concerns fire- Stannard v Gore (2012)
Damage caused by moving fire might be a R v F claim but this is very rare because the thing itself must escape not the fire
The fire itself is not usually brought onto land, the thing that starts the fire in