Basically, they are a combination of a Ranger and Necromancer, like a ranger they use bow (though they have dual axes for close combat), but they have an undead pet, and unlike a necromancer who raises many undead, the Necroranger has just one pet, but the bond between the Necroranger and their pet is unbreakable and much stronger, and the Necroranger can summon a new body for their pet from their necklace. The pet has three forms: Bear (most powerful), Bird Of Prey (most agile), or Wolf (balanced).
Not sure which Tabletop RPG this class would fit in.