Blazes attempt to stay away from the hero, and flee if they get too close. Occasionally, the blaze will stop in place and shoot three fireballs at the player which will light them on fire. If the blaze fireball hits a block, it will set the block on fire. Also, if a blaze takes damage, they get dimmer until they fall apart.

Blazes also don’t take damage from fire effects from items like the Satchel of Elements, but they can be hurt and killed by the flame geysers in the Nether Fortress. If there is fire near them, they will go to the fire and sit there until the fire is out, healing while doing so.

More info: https://minecraft.fandom.com/wiki/Minecraft_Dungeons:Blaze