The Ember is a hostile Mini-Boss spawned in the nether fortress, It looks very similar to the Wildfire, but instead of shields, it has swords as rods.
It attacks by using its swords to slash the nearby target, it also has crown, and it has a amber relic stone on its crown instead of a ruby.
Unlike the Wildfire, which is a boss, The Ember is a Mini-Boss instead because it has lower health maybe?