Spawning. Blazes may spawn naturally in nether fortresses in groups of 2 or 3 at a light level of 11 or less. Blazes spawn from monster spawners in nether fortresses. The spawners are located on small platforms with a three-block staircase leading up to it.
The blaze entity has a unique set of spawn events that can be used in Minecraft commands such as: /summon and /event. (The spawn event parameter is called spawnEvent in the Minecraft help for the /summon command and eventName in the Minecraft help for the /event command.)