"...there is hardly any precise way to predict anything before a said natural phenomenon takes place" - Natori Masatake (Shoninki)
Divination is the attempt to gain insight into a question or situation by way of an occultic, standardized process or ritual. The shinobi had to perform divination before attacking or going on a secret mission.
To throw up three torches, with spikes at the bottom, around an enemy target. The fumes from the sulfur and gunpowder mixtures would force an enemy to surrender or incapacitated. The number of torches that made the enemy surrender would be used to divine a future attack.
The movement and sound of birds in the sky
The direction that the shinobi left home from
The hour and day on which the shinobi left for his mission