It can be a token, a play aide, an ad card, or an art card
Other effects can still modify enchanted creature's power and/or toughness as they would any other creature, and their durations are not affected
This three-mana planeswalker is the Most Expensive Edge of Eternities and generates loyalty from artifact entries, can draw cards for zero loyalty, and tutors artifacts with its -3
Its interesting to play Archenemy with Cube decks and Standard decks, too, as well as kitchen table casuals

Agate Instigator Arcane Investigator Cabal Interrogator Cat-Gator Deadeye Navigator Deepway Navigator Eldrazi Obligator Ethereal Investigator Firkraag, Cunning Instigator Ghostly Castigator Goblin Instigator Goldnight Castigator Gravity Negator Grey Havens Navigator Grishnkh, Brash Instigator Hanna, Ship's Navigator Homicide Investigator Hostile Investigator Hotshot Investigators Instigator Instigator Gang Investigator's Journal Jeering Instigator Klaw, Sonic Subjugator Kor Castigator Leatherhead, Iron Gator Malcolm, Keen-Eyed Navigator Mechan Navigator Myr Propagator Navigator's Compass Navigator's Ruin Persuasive Interrogators Phenomenon Investigators Phyrexian Negator Propagator Drone Purgatory Rootwater Alligator Scriv, the Obligator Scuttlegator Sly Instigator Subjugator Angel Thermal Navigator Tibalt, Rakish Instigator Timestream Navigator Warren Instigator Wojek Investigator

You can even mutate right on top of your walls, which could be useful on ones like Wall of Mulch that sacrifice themselves or other walls to get Nethroi back in the command zone to start reanimating walls all over again