Pros:
* DARK for Chaos, and a better one than Jinzo in most matchups.
* Very similar strengths as Airknight Parshath with the piercing and an advantageous battle effect.
* 300 more DEF than Airknight, which protects it against Asura, Breaker, Tribe, DDWL and other monsters if its flipped facedown.
* Offers more variety on what to revive late-game. You have the choice of reviving Mefist, or Airknight, depending on which effect you need more for the situation.
* Can simpify and reduce the game state. Sometimes you feel like you have your opponent in a corner and you’d rather starve the opponent of options than allow both players to increase their own.
Cons:
* Airknight beats it in battle. And 1800 ATK beaters, while not extremely common, can clash with it.
* Airknight is often preferred because it’s a LIGHT. Thousand-Eyes Restrict already helps up the DARK count while the LIGHT count is often more scarce.
* Late-game, hand floaters (Sinister, Thunder Dragon. Night Assailant), as well as keeping the hand size to 0 can be an out to Mefist’s effect.
Overall, I definitely see why more players run Airknight than Mefist. However, Mefist is still underrated. If Monarchs are in the conversation, Mefist should be as well. Depending on what a deck needs, it could be very good.